Not that I am aware of other than casting numbers on the pulleys themselves, but I'm not sure that matters unless you are a "numbers matching" guy.
At least for RB motors, CAB is correct. In 1972, Mopar switched to a symmetrical bolt pattern on harmonic balancers (& pulley holes). Before that, there was one offset hole in both the balancer & the pulley.
As far as I know, the only mechanically important things are bolt pattern & pulley diameter & number of grooves/pullies on the part vs. your accessories (e.g. power steering, A/C, etc.). The pulley diameter would affect how fast your accessories turn (e.g. "overdrive" or "underdrive" your water pump).
The 440source list is a really good one.
Last edited by PurpleBeeper; 04/25/18 08:34 PM.
70 Roadrunner convt. street car
440+6, NOS, 4-spd, SS springs
'96 Mustang GT convt. street car
'04 4.6 SOHC, NOS, auto, lowered
"Officer, that button is for short on-ramps"
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