Sergent couplers are definitely not for the faint of heart! I don't know how the new couplers are from Innovative Models, but I might find out next week when I visit a friend who just got some.
I converted my fleet over in 2013 or so with a few bulk packs of couplers and lots of dummy couplers. Now the dummy couplers just stay on unit trains and the working Sergent couplers go on everything else.
This is how that tank car started out:
It is an Atlas clay slurry tank car which is a decent match for some phosphoric acid tank cars built around the same time. It has the signature ACF features of the time, which include a control valve and reservoir at the A end and the handbrake at the B end. Speaking of the control valve, I was not happy with it at all so I 3D printed a few ABDX valves through Shapeways and installed them on the three tank cars in my post above. This is a before photo of the control valve, which is really just a lump shaped like a control valve.
Here the car is stripped and repainted with a new control valve and reservoir:
Now I'm adding decals and cobbling together "PHOSPHORIC ACID" from a couple other labels:
Decals are complete, I've replaced the stirrups and flowed some panel line accent into the crossover and manway platforms:
These phosphoric acid cars can get filthy, especially if they've been around for awhile, so I picked out some prototype photos and did some damage:
The area where we spot these cars has some caliche gravel driveways alongside and over the tracks so mud is always splashing up underneath as we switch the cars. I tried to get a little of that on the trucks.
From what I understand the molds for these cars have been damaged so Atlas is not likely to run them again. The last run was in 2003.