Here's the rundown on the aluminum gondola fleet:
By me so I can quote it,
"BN had 3000 aluminum rotary dump coal gondolas, 25 120 car trainsets. The
information following is from looking at photos and discussions on the BN Yahoo
list.
533401-533640 (240 cars) arrived in 1990, drawbarred in 5 car sets. One end was
white denoting the rotary coupler end. Walthers painted their HO scale Bethgons
in this as-delivered scheme. They were soon broken up (within a year or two) and
the paint modified slightly, the totally white end became green with a white
stripe.
In this photo, you can see the extra green panel near the B end of the car and
the green area around the white stripe on the A (rotary coupler) end is a
slightly different shade. Notice too, the two silver posts with extra bolt heads
about 2/3 up the car side. This is where the TWO interior braces attach, not 3
like LBF (is this difference a modification? Where they delivered with 3
interior braces?)
http://www.rrpicturearchives.net/showPicture.aspx?id=1419510
The next group, 533641-533880 arrived in what was the standard paint scheme for
the rest of the coal gondolas.
Left side:
http://www.rrpicturearchives.net/showPicture.aspx?id=1620641
Right side:
http://www.rrpicturearchives.net/showPicture.aspx?id=567979
Since the next 19 numbers are missing from the 1999 ORER, the next series is
533900-533909 (10 cars). This is my best guess here because these are smooth
side cars in an otherwise ribsided series. There may be only 10 cars as it was a
test for a new style of car and BN wanted to test the design before committing
to full trainsets.
http://www.rrpicturearchives.net/showPicture.aspx?id=156489
The next 950 cars, 533910-534859, were similiar if not identical to the
533641-533880 series listed above with a couple exceptions. One order of 240
cars in this series, 534140-534379 was built in 1993 and, like the first order,
came in 5 unit drawbarred sets, some of which may have lasted until the late
1990s. (Message #661 on the BN list indicates 534225,226,227,228,229 are still
in a drawbarred set in September 1999.) One set in this order 534140-534259,
was painted black as an experiment to see if the black helped with keeping the
coal from freezing in the cars and with thawing them when frozen. The drawbars
were supposed to save about 1300lbs per car because there is less draft gear.
Another 120 cars in this group, 534380-534499 were also painted black but didn't
have drawbars. An example of the black cars, BN 534156, can be seen here:
http://www.rrpicturearchives.net/rsPicture.aspx?id=423062
The tubs on the bottoms of the first 1450 cars were flat across the bottom of
the lengthwise tubs, like all the above examples. On BN 534860-535099, 240 cars,
the center of the tubs were built higher off the rail, tapering toward the ends.
Trinity only built 240 cars like this for BN because the design was infringing
on Johnstown America's patent. According to David Casdorph's August 2001 article
in Model Railroading p.34, they were built in 7/94 in Trinity's Greenville
plant. Here is 534892 with "tapered tubs":
http://www.rrpicturearchives.net/showPicture.aspx?id=1388604
The last 1320 cars in the fleet had smooth sides but in two styles and were
known as Aeroflo. 535100-535469, 370 cars, had sides that tapered toward the
center of the car from the last post to the end. The remaining 950 cars, BN
535470-536419 had a step instead of a taper near the ends of the car. Both
varieties can be seen here, tapered end on the left, stepped end on the right.
It is most evident near the top of the car:
http://www.rrpicturearchives.net/showPicture.aspx?id=1055993 "
From message 9652 on the BN Yahoo list.
BN also had a set of aluminum RD2 5 bay hoppers in addtion to the steel triple bay cars. The RD2s didn't arrive until late 1995 or early 1996.