AX5 Syncos

Well.. My synchros are going.. I have problems shifting into 4th gear.. I can shift into all the rest just fine.. I know I can double clutch and get into gear but that is getting old.. I am thinking of getting a new/good used Tranny.. Like an NV4500.. I was thinking if I get that tranny... I can then later upgrade to a 4.0L or whatever later.. From what I have seen at Advance Adapter, I can get adapters for almost any engine... I would rather get an NV4500 then invest in another AX5... What do you think? Good idea, bad idea, in different...

Thanks,

Ben