I have a sportster motor in my garage they said it was a 1972 but I am confused the vin is *3A48359H6* the right side crankcase cast # is a 73, has all the conversion to put the shifting on the left side. What year model jugs fit these base bolts?

 

This may help you
http://www.harley-performance.com/harley-vin.html

 

H6 means 1976. The motor doesn't matter though, it's what is on the frame that counts. Unless you just want to know what parts to buy.

 

That is correct, those cases were used from 1973, when they were introduced (which is what the suffix -73 means) until 1976 inclusive. You can check for part numbers on any of the on-line parts websites like this one.