yolks are cheap and found at any driveline shop for next to nothing. sounds like someone put the wrong driveshaft in it when they converted it to a 400 trans. switch the yolk and it should take care of it. also the jb weld should only be considered a temporary fix as i dont think it would be wise to use for a long term.
Andy
due to budget cutbacks, the light at the end of the tunnel has been disconnected for non payment.