I've got a '73 Challenger Rallye 340 that was built in May of 1973 but the original TQ, a 6319S, shows a date code of 217 2. By my understanding this would be somewhere in July of 1972. This seems really far apart to me. What do you guys think? Everything else on the car (alternator, starter, exhaust manifolds, etc.) is much closer to the build date. Would the factory use a carb 9 months earlier than the manufacture date?

It simply means that it was assembled on the 217th day or 1972, and yes, there were often large gaps in date codes between a cars SPD and dates on carburetors, in some cases over a year.