The CPP trans mount simply bolts to the bottom of the framerail with four 38-inch bolts and accepts Ford or Chevy transmissions. The width of the mount is also narrow enough that it will fit on top of the framerail for mounting, too (if that works better). Proper placement of the trans mount is the first thing you need to determine before moving onto the motor mount installation. It’s a lot easier to make your engine mounts when the trans is mounted solid. When installing a small-block Chevy and TH400 trans, start by clamping the trans mount to the frame so the forward edge of the trans mount is even with the back edge of the front running board mount bracket (in the case of an F-100). With TH350s you can move the mount forward an inch or so; this is also a good starting point for small-block Fords. This should get you close to where the motor needs to be in a front-to-rear relation. Then, I slid the motor and trans into place to see how it was going to fit. When I got it in I saw why the last guy mounted it the way he had. The oil pan and Mustang II crossmember had a bit of a clearance problem. This required some modification to the crossmember. After making some reference marks on the crossmember for the oil pan width and forward edge, I removed the engine/trans and laid down some accurate cut lines, plasma cut out the needed material, and ground the edges smooth. With some card stock, I made up templates for the filler pieces I needed and cut them out of 1/8-inch plate. They were then tacked in place.
Back in went the engine and trans, and the oil pan fit perfectly in the new notch in the front crossmember. This, in turn, allowed the proper positioning of the fan and shroud. In this case, other usually critical clearances didn’t need checking. I had plenty of steering/exhaust clearance, the trans pan cleared the stock trans mount crossmember, the engine-to-firewall clearance problem was solved, and the oil pan cleared the rack-and-pinion. Once I was pleased with where the engine sat, I drilled the needed holes to bolt up the trans mount. It’s a good idea as you’re bolting the transmission to the mount to double-check that the trans is centered in the frame. In my case the measurement to center was 17 inches. Drilling those holes in the frame is never my favorite part. I always start with a small drill first, say 3/16 or so, then 5/16, and then the needed 3/8 inch. With those chores done I’d completed the hardest part of the motor/trans mount install.