3973086 70-81 Camaro/Firebird
General Motors Part Number 3973086 Z Bar Frame Bracket
0.852 BRACKET, Lever and Shaft
70-75 ALL F M.T. (Chevy Parts Books)
76-81 F (Chevy Parts Books) (Pontiac Parts Books)
Factory correct applications are your responsibility. GM made part and part # changes with no rhyme but a reason (no production interruptions at any cost).
Application charts are for replacement parts that were available at the time of parts book printing.
My observations come from the parts I have in my collection or other reliable sources your parts may differ.
If Factory correctness is your goal, do more research, join car clubs,
forums and buy an assembly manual if one is available for your Project Car (you wont be sorry).
This is a fun and interesting part of the hobby!