I sent Monte an off net email earlier in the week. I suggested that he use the OEM equivalent AC Delco 15-4208, or 15-4216, or the 15-4947. All of
these are the same "Heavy Duty" specs as the OEM GMC clutch. I also gave him the 15-4644 number in case he wanted the noisier, and faster "severe
duty" clutch. It turns out that AC Delco used different part numbers for the same clutch depending on which car manufacturer it was going to. (Buick,
Olds, Pontiac, GMC, etc.) Now 30 to 40 years later with very decreased demand, they have consolidated the numbers down. So you will find many of the
original numbers are obsolete. It makes stocking multiple numbers unnecessary when a single number will do. If you look up a 15-4947 you will see it
listed for multiple years of Olds 455 cu in. engine powered cars.
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Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana