I think that there is only one surviving 36" RR in Pennsylvania (the EBT).
Most rolling stock was pre 1900 and only: box, flat, hopper, tank ... etc ... and such existed.
Perhaps in other produce and grain growing States, there was more widly varried rolling stock such as in Colorado.
There are some nice 36" Tranz sites ... SanJuan ... Cowboy ... I can't remember them all.
You could swap out NG trucks on SG rolling stock in the config file.
The EBT RR actually did this truck swapping out thing on the prototype.