A500 42RH Crossmember template?

Even the USCT cross member comes with the pad for mounting the trans mount separate to be welded to the cross member in place once the trans with the trans mount and pad are in position. I think that answers your question? What are you using to shift the transmission? How do you plan to shift into OD and engage the lock-up torque converter? The 42RH is significantly different from your 904 and you should be prepared to do a good deal of fabrication and fiddling to get it in place. This is NOT a quick job, but as you seem to be doing, there is a lot that can be done before you swap the trans. I just can't imagine doing this on a car that I need to have up and running quickly. You need a custom driveshaft length. What car is this going in and what is the rear end? If it is a 111 inch wheelbase like a Dart (NOT Dart Sport or Demon) with an 8 3/4 there are a few of those out there and you can get driveshaft measurements from completed projects from other FABO members. You would have to post a query if it is a Duster/Demon body, but I bet there are some out there.