71 Alternator Pulley, PS and AC

[Frank B.]

This is a two part question regarding the Alternator Pulley on a 71 Big Block with AC and Power Steering.From what I can determine the GM Part Number for the pulley is 3883978 which is stamped on the face of the pulley.The first question relates to the original finish of the Pulley. Is it plated Zinc, gold Iridite or is it painted ? The reason for the question is that I located a NOS pulley with part number , however the vendor is telling me that they were painted Gloss Black. I find this hard to beleive. The second question relates to the judging of the Alternator. I can find nothing in the judging manual concerning the part number on the pulley ,it only discusses having the correct alternator. Does this mean I can use a after market pulley on a original alternator without getting a deductio?

[Joe L.]

Re: 71 Alternator Pulley, PS and AC

Frank-----

The GM #3883978 pulley was used for a number of years. It was originally used in PRODUCTION for the 1966 model year and last used in PRODUCTION for the 1974 model year. It was available in SERVICE from December, 1965 through August, 1999. So, this part may have changed in minor ways over the years of its existence in the GM parts system. As far as finish goes, I believe that examples produced at various times were silver zinc (or cadmium), dichromate bright dipped ("gold"), or painted. Usually, pullies used in PRODUCTION of this part number did not have part numbers stamped on them. Some may have, though.

In any event, the 3993978 pulley usually used in PRODUCTION for the 1966-72 period was silver zinc with no part number.

[Frank B.]

Re: 71 Alternator Pulley, PS and AC

Joe

Thanks for the pulley infromation,it was very helpful.