Question on part numbers and what supercedes them

[Mike Cobine]

While trying to locate the correct pulleys for my car, I found the following:

Crank:
3791684 - not listed, AIM shows for C60
3825433 - not listed, AIM shows for C60, (superceded 3791684?)
3744043 - dbl gr 6-5/8" Stock 1963

What are 3791684 and 3825433 equivalent to today?

In the 1983 Corvettes parts and Illustration Catalog, these are shown but not as replacements for 1963.
3858533 - dbl gr 6-5/8" '62-73 hp, s/hp, exc ac non-63
3850838 - 7-21/64" w/ac, exc s/hp some years, s/hp other years, 64-70, grooves unknown

Water pump:
3790356 - ? gr, 7 dia, normal match to 3744043, stock for 1963
3770245 - dbl gr, 7-1/8" stock for L-76
3840463 - for C60, dbl gr, ? dia, current replacement is ??, normal match is ??

Can anyone tell me more on the 3840463 as to size and what is equivalent today?

Thanks

[Joe L.]

Re: Question on part numbers and what supercedes t

Mike-----

Here's what I can tell you:

1) First, GM #3791684 was a waterpump pulley, NOT a crank pulley. It was discontinued in August, 1963 and replaced by GM #3840463. The latter pulley was discontinued in February, 1969 and replaced by GM #3905989. GM #3905989 was a 2 groove pulley of 5-3/4" OD. It was discontinued without supercession in September, 1983;

2) I can find no record, at all, of GM #3825433;

3) GM #3744043 is a 2 groove crank pulley of 6-5/8" OD. It is still available from GM for a current GM list price of $39.36;

4) GM #3790356 was a waterpump pulley that was discontinued in September, 1974 and replaced by GM #3900434. The latter pulley was discontinued without supercession in May, 1990. I don't have specs on either pulley;

5) GM #3770245 is a 2 groove, 7-1/8" OD waterpump pulley. It is still available from GM for a current GM list price of$64.77.

Your other observation is mostly correct: GM #3858533 and GM #3850838 are both crankshaft pullies shown in the 1983 P&A Catalog. Both are 2 groove pullies of the dimensions you noted. GM #3850838 has no 1963 Corvette application and is discontinued. GM #3858533, however, is applicable to 1963 Corvettes with 340 and 360 hp engines. It's not the original pulley used, but it's been the SERVICE replacement for MANY years. It's still available from GM for a current GM list price of $40.63.

The discontinued pullies mentioned above are likely available in reproduction from Goat Hill Classics aka Paul Baker, "The Pulley King".

[Mike Cobine]

Thanks - Re: Question on part numbers and what sup

Thanks very much for the information, Joe.


I went back through what I had and see I misread the assembly drawing. The crank pulley callout was left without a part number. My copy has the notation marks faded out and when I found "3791684 pulley" in the revision section, I assumed it was to the blank crankshaft pulley number. Instead I see now it was the former water pump pulley replaced with 3840463 like you said. The drawing has an ECR 51082 listed. The month is missing but the date shows 6-63. This would have to be one of the pages that was a bad copy.


The 3825453 number came from the next revision line, however, checking back, I see the faded note symbol and that it should go to the "generator pulley" callout, even though we know it is an alternator.


Brace 3825453 went with alternator pulley 1949358 and no date on change. The then current brace 3825463 went with new pulley 1949355. This was with Alternator 1100633. What are odds of the brace being 10 off?


Thus it seems the pulleys are:

Engine Crank Water Pump Alternator Production Notes
Base 3744043 3790356 1958095
L75 - 300 3744043 3790356 1958095
C60 3744043 3791684 Date ended unknown
C60 3744043 3840463 Date added unknown
C60 1949358 Date ended unknown
C60 1949355 Date added unknown
PS Addition 3751232
PS Pump 3770509
L76 - 340 3770245 3770245 3829193
L84 - 360 3766987 3770245 3829193





Thanks again, Joe, for helping fill in the blanks.