Semper Fi, Buddy,
I'm not positive about the '66s but the previous owner shoehorned a 454 (from a '77?) into the engine bay of my '67 Suburban 4x4. He converted from a SM 465 to a TH350 tranny (I assume) because the big block stock exhaust manifolds interfered w/ the Z-bar action. There are ways around that like hydraulic clutch servo, but that's outside of my scope of knowledge.
While the body styles were way different between these model years, the pre- '69s' frames had much in common with the '60- on types.
Good luck. OBTW: I was stuck on the Rock with VMA-513, myself about 25 years ago.LOL.
