Sent off the carb from my '63 Avanti R1 to Dave Thiebaux for rebuilding assuming it was the Carter 3506s OEM carb. TUrns out, it wasn't. It's a Carter 3721SB that was used primarily on Vette 327's in the early 60's. Not certain why the previous owner made the swap. I had driven the car for about a year before putting it on the lift recently for some brakework, with no fuel-related issues that I can recall. My question - what are the differences between this carb and the 3506s? Am I setting myself up for future problems if I re-install it? BTW, an absolutely beautiful rebuild job by T-Bow!