This might help to clear up the differences with some clamshell engine mounts. It’s not hard to see when someone shows you a side-by-side comparison, but these are parts that are commonly mixed up when customers are purchasing for their Chevrolet.
The upper is a normal Chevrolet 305 or 350 engine mount found in V8 73-81 Camaro’s, in Chevy in general up to mid-90s commercial also. Buick and Olds mid 70s and 90s and Pontiac Firebird TA with the Chevy engine from 77 to 81 and all 82 - 91 Firebird & Camaro V8 share the upper also.
These are not the same as Pontiac mounts from mid-70s to 1981 models with V8 real Pontiac engines in them. Those are more likely recognised as they have a flat top, also Olds 403 (PW10970).
