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Diesel Detail Freak
I've been teasing with building three SD39's for some time now, but I have avoided it because of the effort it'll take. Now I reailze that the Hi-tech sides; coupled with Cannon doors, hatches, grills, fans hood end & radiator roof; plus an Athearn dynamic unit; and a Kato SD40 make a complete SD39! BUT, I'm not so sure on the cooling fan spacing of an SD39, (1) does it match an SD38 (I'd assume so)? (2), Does the GP39 match the SD38's fan spacing? If so, the GP39 should match too, (3) making all 4 match, right? If all 3 steps previously mentioned match, I can use a Plano GP38 fan hatch to make the SD39's, saving all the careful measuring.



Been Nothin' Since Frisco
Use the GP38 hatch and you'll be fine. It was a little ways into the Dash 2 line that the fan spacing got closer.


Diesel Detail Freak
Thanks Ryan & René! Looks Like I'll order the parts soon, and start. David says to use a P2K SD45 walkway, with a Kato chassis, hummm. I think the Kato SD40 matches though, in my mind it looks correct, plus its easier, and a whole heck of allot cheaper then buying 3 Kato SD40's and 3 P2K SD45's! The only detail I have to watch is the brakes, as it looks as if #6200 only has one cylinder!
Thanks Ryan & René! Looks Like I'll order the parts soon, and start. David says to use a P2K SD45 walkway, with a Kato chassis, hummm. I think the Kato SD40 matches though, in my mind it looks correct, plus its easier, and a whole heck of allot cheaper then buying 3 Kato SD40's and 3 P2K SD45's! The only detail I have to watch is the brakes, as it looks as if #6200 only has one cylinder!

I think he started these loco's way before the Athearn/RPP SD40's arrived. The updated chassis and fuel tank and most important the excellent Athearn side frames (both hi and low mounted cylinders, so you can have one low and one hi mounted cylinder on your sideframe)) are a good starting point for your SD39.
I'm using Athearn/RPP SD40 frames and P2K shells to built my SP SD45's.




Been Nothin' Since Frisco
Dave may have used the SD45 walkway to ensure the end of the blower duct is in the right position or to get the correct stepwell/pilot shape. I don't know for sure what the answer is, since I don't model SP or SD39s, but I do know there are different variations within the SD45 line on those two spotting features.

I agree with Rene that the Athearn underframe and fuel tank is superior to the Kato underframe and fuel tank, but I doubt that had much sway with Dave, since he replaced all the offending parts with Cannon details anyway. Not only that, he owns and operates a mill, so nothing stands in his way! I'm thinking it was the superior Kato drive line that he was after.

If I were you, Josh, I'd examine the blower duct and step arrangements on the prototype and compare them to the P2K and Kato parts before committing to building one of these. If you're going to scratchbuild something, take nothing for granted and get it right or it will bother you forever.


Fun Lover
I'd love to get to the point where I can comment on a thread like this, but I just learned how to tell the difference between a GP-40 and an SD-40. An SD39 is just asking too much.


Diesel Detail Freak
The step arrangement is the same between the Santa Fe SD39's & the Kato SD40. Now the blower duct is another issue, I hadn't thought about it. I'd prefer to avoid the newer Athearn offering for one main reason, I'd have to saw the bugger down to the walkways anyways! Thus why a P2K SD45 or Kato SD40 come out on the winning end there.

I know for a fact though, that Santa Fe SD39's are different then SP ones, that has become evident in allot of reading...

The WHOLE long hood is scratch, from kits, so if I were to use an Athearn SD38/40, I'd have to saw the whole long hood off, how's the nose & cab on them? With the SD45's I'd have to add to the deck, so an SD40 would be prime, the Kato SD40 has it all, so far.

Before now, I hadn't though about using a Plano fan hatch, I'm going to order the SD45 this coming week, for an SD40-2 with an SD45 radiator section.


Been Nothin' Since Frisco
If you get to see the Plano hatch before you buy it (read: you're not ordering it online but picking it up at a hobby shop), then make sure you get one of the stainless ones and avoid the phosphor bronze ones like the plague. I'm pretty sure Keith doesn't use the phosphor bronze anymore because the stuff can get a curl in it and stay forever spring-loaded, which means you'll lose any battle in attempting to stick it down.


Been Nothin' Since Frisco
I'd love to get to the point where I can comment on a thread like this, but I just learned how to tell the difference between a GP-40 and an SD-40. An SD39 is just asking too much.

It's not that hard, Chip, at least with EMD locomotives. You've figured out the main difference - GP means B-B or four powered axles and SD means C-C, or six powered axles.

After that, look at the exhaust(s). One large rectangular stack closer to the cab from the middle of the long hood and it's a turbocharged engine, two (or sometimes four) smaller oval or round stacks roughly centered on the hood and it's a normally aspirated engine.

Number, size and position of fans is a big indicator of what you're looking at, too. The fans you see over the middle of the long hood on some engines are dynamic brake cooling fans, but dynamic braking is an option, so some locomotives don't have them at all. This option has nothing to do with determining the model of locomotive, though, but it's important to distinguish radiator fans from the dynamic fans when making an ID on a locomotive.

The radiator fans are at the end opposite the cab and usually have large rectangular grilles under them on the hood sides. Some variations on EMD locomotives did not have the typical round fan and grille arrangement and instead featured an angled grille pair on top and large see-through intake grilles on the sides just above the deck. This variation is common to the SD45T-2 and SD40T-2 of the six axle variety and to the GP15, GP15T and GP15-1 in the four axle variety (I'm not counting the switcher type for this example).

Other successful models were improved throughout their production runs and these improvements often led to new phase designations (which I won't get into here to avoid complicating things more than they are at this point), but could also lead to new model designations. A good example is the set of changes adopted to the EMD catalog in 1972 known as the "Dash 2" line. The 1972 locomotives were different enough from their earlier counterparts that a new model designation was required, so "SD40" became "SD40-2" and "GP38" became "GP38-2" and so on. This set of improvements was largely internal, but the most obvious is the "water sight glass" which is an oval window on the engineer's side at the front of the radiator, which allowed an inspection of the radiator water level without opening a hood door. There are other differences, but some are too subtle to pick out in the average photograph and others, such as truck type, varied with the individual railroad's specifications of equipment or the use of recycled parts.

Now, to get down to the difference between an SD39 and any other SD type locomotive of similar vintage, let's look at the fans. An SD39 has two radiator fans and the much more common SD40 has three. Like the SD40, the SD39 is turbocharged so it has one large exhaust. The SD38 also has two radiator fans, but it is normally aspirated, so it has at minimum two smaller exhaust stacks. Why only two on the SD39 and three on the SD40? The 40 line used the 16 cylinder diesel and the 38 and 39 line used a 12 cylinder diesel, so with four fewer cylinders to generate heat, only two fans are needed.

Change the number of powered axles to four and we're talking about GP38s, GP39s and GP40s. The spotting features are the same, as far as exhaust type and number of fans are concerned, so once you have this down it's easy to spot the difference and ID a locomotive right away.

There are numerous locomotive models produced by EMD over the years and virtually any of them can be identified based on the criteria I listed above. Again, these are:

  • Number of powered axles
  • Number and type of radiator fans
  • Number and type of exhast stacks
  • Dasj 2 spotting features, such as water sight glass

I know you're into the steam era, but if you want to know how to ID any EMD locomotive quickly and easily, I can give you the skinny on the various models.


Fun Lover
Thanks Ryan,

That took a lot of effort, but it makes it a lot clearer. I'll start looking for the differences. Around here, Norfolk Southern is kind enough to paint the model on the side of the cab. When I go railfanning, I can tell everyone exactly what type of engine it is and sound impressive. Mostly that's my son and he doesn't really care.


Diesel Detail Freak
LOL Chip, always a good thing isn't it. Its not that easy with Canadian locomotives, until you get to learn what their types mean... Such as (most notable to me now) the GF-636a, AKA SD50F. If I'm remembering right (please correct me Ryan!) its General Freight - 6 axles, 3 per truck, 6 powered.

Ryan, you left out a key note for Chip...

The SD38, SD39, SD40, & SD45 share a chassis, based on the SD45's engine size & space requirements. When the Dash 2 line came of light, the SD45-2 needed more space, the frame was lengthened, so then the SD38-2, SD39-2, SD40-2, & SD45-2 all share a slightly longer chassis, based on the SD45-2's needs. Thus why the SD38/39/40 & SD38-2/39-2/40/2 have the porches.

So, realizing that, the GP38/39/40 should be the same, as its the same engine, on 4 axle trucks, based around the needs of the GP40's engine (same with the GP38-2, GP39-2, & GP40-2). If the SD38 & GP38 share an engine, then the cooling fan hatch should match.

Some good learning going here...
Close Josh, but the last two numbers are the horsepower (Rounded down to the nearest hundred)
This goes for the SD50Fs, even though they have been derated to 3200hp


Sorry Guys, but you're both wrong. The Canadian classifications vary by the railroad.
For CN and VIA Rail:
the first letter is the builder
E = GE
G = EMD (or GM)

the second letter is unit type
F = Road Freight
H = Hump
P = Passenger
R = Road Switching
S = Switching
Y = Yard

the third letter (if it has one)
A = 'A' cab unit
G = steam generator equipt
L = lead hump unit
T = trailling hump unit

The numbers following the dash
If two numbers, they are the horse power rounded down to lowest hundred
If three numbers, the first is powered axle count with the last two being the horsepower rounded down to lowest hundred

The small letter at the end is the order group the unit was in 'a' for the first order, 'b' for the second, etc.

CP Rail is different:
DRF = Diesel Road Freight
DRS = Diesel Road Switcher
DS = Diesel Switcher

the two numbers after the dash are the horsepower rounded down to the nearest hundred

the small letter at the end is the order the unit belonged to.

So an SD50F GF-636a is a General Motors Road Freight with 6 powered axles and about 3600 horsepower (when delivered) from the first order a of SD50F's

Both of these classification systems are in addition to the builder designations. So an SD50F is still an SD50F. CP units have both the builder designation and the Class designation on them.

BNSF dude

BNSF foamer
Remember, The SD38-2 is a GP38-2 engine in an SD40-2 body so every thing is essentially the same for cooling systems and fan spacing.

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