Hi, I've just created a QD train that contains the AP Class 86 and the FSA / FTA freight cars. Unfortunately, whenever I choose the train and choose any route, the TS always crash. I think the error could be the Train.
Re-install your Class 86 pack (through Steam), then re-install the enhancement pack. That's fixed similar issues I've encountered. Interestingly, moving my install to my laptop's internal Hard Drive from an external one I shared with another computer has, seemingly, fixed the issue.