Correct Speedometer Adapter 67 L78 D70-14 4.56 Rear

[jbtech]

Looking at the parts history it seems that the part numbers 735 and 756 adapters "appear" in November 1967 since they replaced older part numbers 655 and 497 in August of 1967. Perhaps I bought the wrong part?

[jeffschevelle]

Originally Posted by jbtech

Looking at the parts history it seems that the part numbers 735 and 756 adapters "appear" in November 1967 since they replaced older part numbers 655 and 497 in August of 1967. Perhaps I bought the wrong part.

Thanks! I should have thought to look at the superceded numbers book too! Very helpful.

That page does suggest that the July-67 book is wrong where it says 6476655 was for 4.88 Z28. Since it was replaced by 6476735 (which is 4.56), presumably 6476655 was also for 4.56.

Likewise, since 3905497 was replaced by 6476736 (which is 4.10 and 4.88), presumably it was also for 4.10 and 4.88.

However, since 67 Z28 tires are presumably taller than the regular 14" tires, maybe a 4.88 with 15" wheels was close enough in final drive ratio to a 4.56 with 14" tires, so used the 4.56 adapter?? If so, then the July-67 book would be correct on that one application, but the Nov-67 book would have to be wrong. I don't see how they could both be correct ...

[jbtech]

More information from a P&A catalog dated spring of 1967.

[jbtech]

Here are the teeth counts and color based on speedometer driven gear part number.