Part Number Cross Reference

[Alan Nicholas]

Gents & Ladies.
Is there a cross reference table for part numbers for transmission gears? In that GM/Chevrolet parts have different part numbers than gears that have been manufactured by the Perfection Gear Company (and I assume any other after market parts manufacture). I assume that somewhere there is a conversion table, because to manufacture after market transmission parts for various vehicles makes and models without a cross reference table would be madness.........wouldn't you think??
The reason I ask is because I have C15A parts book that tells you all the part numbers of the transmission in Chevy/GM numbers, but on eBay that isn't always the case. Often I will find a gear that sounds correct in the description (size, number of teeth etc) but has a Perfection Gear Company or some other manufacture number. When they are asking, at times, some steep prices for these items, I can't bring myself to purchase the said items, especially if there is a no return policy as a lot of these sellers do have.
Any help would be appreciated
Regards
Alan Nich