Is there anywhere to find applications and PN listings for flywheels? I've collected three, and am unsure of what they are. I putting a 4-speed in a 68 that had an auto. Here's the numbers.
3988989 N (the last digit might not be a 9?). Wear pattern is 10.5", date code L 2 5. I've heard the "N code" is a better part?
3729004, wear pattern 10", date code C 12 4.
3768783 (the 6 might be wrong). Wear pattern11", date code L 21 6.

Is there a minimum thickness? Two of them look to have never been resurfaced.
Thanks

The numbers on the 'wheels are casting numbers, not part numbers. Usually the part number is one digit higher, like 3988989 would be part number 3988990. I don't know of a source for the casting numbers, although I'm sure there is a list somewhere.

If you have a 454, you need a flywheel for a 454 only, external balanced engine. just bought a GM flywheel (for 11' clutch) for my 454 from Chevy dealer over the counter. $174
Doing the same as you, changing to 4 sp. from t400 in a 71

I'm using a 307, no external balance... Since these are all date coded before the 454 or 400 were made I assume they're fine for my application. Just trying to find out what they are (and if they're worth ebay!)