Well, I've got a little time now so I'll offer the second part of this three part series. First, though, I'd like to mention that although I'll be covering the 63-70 models, it is possible that 63 Corvettes used a different driveshaft u-joint than the parts that I'm presenting here. No doubt about the fact that its size and general configuration are the same, but the actual part number may have been one that I haven't discovered yet.
Diveshaft Universal Joints---All 63-67 and 68-70 With Manual Transmission
63? to mid 65
During this period, Corvettes were originally equipped with driveshaft u-joint GM #3849500. This u-joint used a "round" trunnion which was 1-5/8" in diameter. The trunnion had a round, indented center on both sides with a diameter of 1". The number "3842024" appears on the trunnion forging. There are no lube fittings nor undrilled bosses for lube fittings. Bearing caps are 1.06" in diameter and have a slight indention on the ends with no markings whatsoever. Seals are black rubber/plastic. I believe that this u-joint may have been of internal GM manufacture.
mid 65 thru 1970
During this period, Corvettes used driveshaft u-joint GM #3889690. This u-joint had a "square" trunnion design with square indentions on both sides of the center of the trunnion. On the trunnion forging appears "Spicer" and several other manufacturing numbers. There are no grease fittings nor bosses for grease fittings. Bearing end caps have slight indentions on the ends and the word "Spicer" and "USA" are stamped or cast into the center of the ends . The number "591" is also stamped into the ends. Seals are black rubber/plastic.
U-joint GM #3889690 was available in service until 1973. In 1973 it was replaced for service by GM #3955571 and in 1974 this part was discontinued in favor of GM #2448382. Both of these u-joints have grease fittings and were service-only parts since this size u-joint was not used on any production Corvette during the 71-79 model years.
In 1975, service u-joint GM #386451 replaced the earlier part numbers. This u-joint has a "square" type trunnion with the manufacturer's name "Spicer" cast on the trunnion. However, it does not have indented trunnion centers like the production #3889690 u-joint. Also, it does not have grease fittings, but there is a cast boss for grease fittings. Bearing caps have slight indented ends and the word "Spicer" and number "621" either stamped or raised in the center of the cap ends.
Part number 386451 was discontinued in April, 1990 and replaced by part number 7849090. This part was, in turn, discontinued and replaced by GM #26015249 in September of 1991. GM #26015249 uses a 1-5/8" round trunnion with a round indention on the center of both sides and no grease fittings or bosses. Bearing caps have slight indented ends with the number "15" stamped into the ends of each cap and seals are black rubber/plastic. I mention the configuration of this replacement-only u-joint since its configuration is, interestingly, very similar to the original 63-65 u-joint, GM #3849500.
Well, that's it for now. I'll post "Universal Joints---Part III---Driveshaft U-Joints 68-to 70 with Turbo Hydramatic and 71-79 All" in the near future.
Diveshaft Universal Joints---All 63-67 and 68-70 With Manual Transmission
63? to mid 65
During this period, Corvettes were originally equipped with driveshaft u-joint GM #3849500. This u-joint used a "round" trunnion which was 1-5/8" in diameter. The trunnion had a round, indented center on both sides with a diameter of 1". The number "3842024" appears on the trunnion forging. There are no lube fittings nor undrilled bosses for lube fittings. Bearing caps are 1.06" in diameter and have a slight indention on the ends with no markings whatsoever. Seals are black rubber/plastic. I believe that this u-joint may have been of internal GM manufacture.
mid 65 thru 1970
During this period, Corvettes used driveshaft u-joint GM #3889690. This u-joint had a "square" trunnion design with square indentions on both sides of the center of the trunnion. On the trunnion forging appears "Spicer" and several other manufacturing numbers. There are no grease fittings nor bosses for grease fittings. Bearing end caps have slight indentions on the ends and the word "Spicer" and "USA" are stamped or cast into the center of the ends . The number "591" is also stamped into the ends. Seals are black rubber/plastic.
U-joint GM #3889690 was available in service until 1973. In 1973 it was replaced for service by GM #3955571 and in 1974 this part was discontinued in favor of GM #2448382. Both of these u-joints have grease fittings and were service-only parts since this size u-joint was not used on any production Corvette during the 71-79 model years.
In 1975, service u-joint GM #386451 replaced the earlier part numbers. This u-joint has a "square" type trunnion with the manufacturer's name "Spicer" cast on the trunnion. However, it does not have indented trunnion centers like the production #3889690 u-joint. Also, it does not have grease fittings, but there is a cast boss for grease fittings. Bearing caps have slight indented ends and the word "Spicer" and number "621" either stamped or raised in the center of the cap ends.
Part number 386451 was discontinued in April, 1990 and replaced by part number 7849090. This part was, in turn, discontinued and replaced by GM #26015249 in September of 1991. GM #26015249 uses a 1-5/8" round trunnion with a round indention on the center of both sides and no grease fittings or bosses. Bearing caps have slight indented ends with the number "15" stamped into the ends of each cap and seals are black rubber/plastic. I mention the configuration of this replacement-only u-joint since its configuration is, interestingly, very similar to the original 63-65 u-joint, GM #3849500.
Well, that's it for now. I'll post "Universal Joints---Part III---Driveshaft U-Joints 68-to 70 with Turbo Hydramatic and 71-79 All" in the near future.
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