Alternator Pulley #3829387
 

Alternator Pulley 3 5/8" deep groove. 1967-72 396, 427, 1965-68 327/350HP, 1969-70 Chevelle, Z-28 302. $125.00 plus shipping.

I believe the Z/28 pulley is 3.2" and does not have a part number showing.

You could be correct. My research tells me that this alternator pulley was used for the Z/28. Maybe this alternator pulley was used for the 350 cubic inch engine not the 302 cubic inch engine. Can someone else give some input so I can make any corrections.

67 Z28 and I don’t know what year when they started but midyear Corvettes with the L 79 engine got this pulley

Your #3829387 Alt. pulley has an outside diameter of 3-5/8",and a shaft Dia. of 4-3/64",with a 1/2" wide Deep belt groove.
Was used on:
1965-66 Impala series w/spcl.Hi-perf 396.
1966 Chevelle w/spcl.Hi-Perf 396.
1967 Camaro w/302.

More sought after Alt. Pulley #1970831 has an outside Dia.3-3/16".shaft Dia of 11/16" with a 1/2" Deep belt groove.
No identifying numbers were stamped into this pulley.
Was used on:
1969-70 Chevelle w/solid lifter 396,454
1969 Impala series w/solid lifter 427
1969-70 Nova w/solid lifter 396
1969 Camaro w/solid lifter 302,396,427~COPO
1970 Camaro/Nova w/LT-1 350