I working on a deal to purchase a 455 motor. My question is, Are all the Buick,Pontiac,and Olds 455 the same motor. You know like how they used Olds 403's in 2nd gen T/A's. I've always been more of a small block man and I don't have a lot of knowledge on the larger displacement motors. Any help would be great.

 

Buick, Olds,and Pontiac each had their own design for their 455.

The only one I've seen any 3rd gen support for is the Pontiac. See sticky above.

 

Only from 77-79 did GM put the Olds 403 into the Firebird but only after dropping the Pontiac 455 after 1976. The second gen platform was easier to drop in a B-O-P 455 or Chev BBC since the 2nd gen platform originally came with a big engine at one time.

Because the B-O-P-Caddy engines all share the same bellhousing bolt pattern, it was easy to pull the Olds engine and drop in one of the others for those dihards who still wanted a Pontiac engine under the hood.

By 1982 when the third gens were released, all the f-bodies got the Chev engines except for the few who got the Pontiac 4 cylinder or Buick V6.