Here are a few pics of installing the rear coupler on the A unit
I don't know if theres a better way of doing this but I decided to just do it
I used the existing coupler adapter but shimmed it with 3/8” styrene spacer
Also drilled 2 new holes for the 2 2/56 x1/2” machine screws to afix to the chassis
A modified Kadee # 805 was installed for closer coupling
Here are some pics of the work so far