5.3 ?

I searched and didn't find what I was looking for so here is my question.

Dropped a 5.3 into an '86 Suburban chassis using AA engine mount adapters. I'm going to have to modify the engine cross member for pan clearance. The right hand exhaust manifold looks like it is going to clear but the right hand side doesn't look like it is going to work without some frame surgery.

Has anyone here put a gen III small block into a '73-'87('91) Chevy 4x4? Are the f body manifolds narrower and will they clear?

Gus

Fbody stock manifolds are a lot tighter against the transmission.