called eaton Detroit springs, and they say the only difference between a 43 vs a 44 is the bushing in not present on the 44.
But show the same spring construction and arch. I guess GM has the same type of part number like changes (if the bushing is with the spring of not). Does a convertible have a different bushing?

So can someone tell me if the 3400044 is the right spring for a 340 convert? I hate to send them my bottom leaf (which has the pn) to attach to a new spring assembly, if its the wrong pn overall.

They said they definitely are a heavy duty spring. I did enough calls to spring shops, and they said re-arching is a short term fix, they will relax back down to the sag the spring once had.