| If the sound is weak and you think that the body is the culprit, it could be worth a try, but you don't really know what improvements will come after the swap.
I'm thinking a couple of things. My first idea is that the bass may have some value now and if you wanted to unload it for another one, you could keep it "as is". If it's sort of a parts bass that someone put together, that's another story. Less value to preserve. Lots of good parts out there, including bodies, if you take a little time to shop around.
I'd only appreciate a US Fender body in an original bass - that's just me. I rarley see much current stuff from Fender that seems as substantial as other gear. The first body I'd want to look for would probably be something from Warmoth. The last Jazz I picked up actually has a crack in the body that was there when I spotted it in the store, but because it's a Warmoth, I wasn't afraid to give it a home. This bass played fine in a couple sittings at the shop and I've never seen anything from that bunch that wasn't decent. | 
