Would a 350V8 engine from a 1996 Suburban fit in a 1969 C10 stepside pick up w/out modifications?

The 350 will easily fit in the bay of a 69 C10 P/U. As for a direct bolt on,unlikely. I am sure the Nissan block and Chevy block will have different motor mounts but it's an easy fix to swap out the mounts. Another thing you may want to look at will be the tranny crossmember, that will most likely need replacing also. The 350 having a carb is no big deal,your gas mileage won't be as good as a fuel injected motor but that can also be fixed rather easily. The car value will not go down but won't increase greatly by the swap either, honestly in my opinion a chev truck should have a chev heartbeat (motor).

it should fit right in . the big difference is that all the 96 engine bolt treads are metric & the 69 is american standard . do dot try to put a bolt from one engine to another.