I just swapped a Chevy 350 out of my '69 and replaced it with a '74 Pontiac 400. Summit has the frame and motor mounts and I did not have to change the crossmember or the driveshaft length. I also swapped a Chevy TH350 for a BOP TH350 at the same time. There was a boss on the 400 motor that blocked the one motor mount from sitting flush, I had to remove some material from the motor mount and then everything fit perfectly.