Has anybody put a 400 pontiac in an 84 cutlass? What does it take ? The car has a 260 olds now , do you have to change motor mounts or motor mount location? Would it be about the same as swaping in a sb chevy? ANY info is welcome.  

it should be the same a 400 is considered a smallblock by chevy so pontiac shouldn't be any different  

What year is the Pontiac engine?  Pontiacs have an early (1950s-1960s) and a late (1970s) mount system ( I don't have my old H.O. Racing catalog in front of me so I can't be more specific--I just recall one is a "two bolt" and other is a "three bolt" set-up)

But if you have the late Pontiac 400 (which has virtually nothing in common with an SBC 400, BTW--except for the ball-stud mounted rocker arms that Ed Cole hijacked from Pontiac), you should be able to use the the 1978-81 G-Body motor mounts for a 301 or 265 Pontiac. 

My distant recollection is that this is a fairly easy swap (except for maybe some hassles with the odd-ball factory transmission crossmember, which does not adapt well to true dual exhaust set-ups.