First of all, good luck getting your hands on those Red Caboose Unimate's. The process is very simple, they're just T-shank couplers but I do recomend taking the trucks out (still easy to do) to change the coupler. On the B-unit I wedged a piece of styrene, I think .020" or .030" behind the coupler to keep it in there solid. I used the stock coupler spings on the A-unit couplers, but if you have two sprung couplers together the units will bang into eachother when slack runs in. Thats why the solid couplers on the B-unit, even then with slack run in the units are about .005" apart or less.
