I wish I'd thought to take pictures... back in late 70s a guy I did business with dropped a Detroit 4-53 into a Chevy pickup. It was mean!! I know they had oil pan cross member issues but the guy was a welder so he solved it somehow.

Old 70-80's chevy trucks came with the 4-53 detroits in them factory so there should be an oil pan that would work to prevent doing a frame crossmember alteration.

This would have been late 70s 7 truck wasn't new... might have been 60s. In any event, retrofitting required changes. I was into fast cars & diesel trucks came later.