IF the sheet metal is good buy it. If you change your mind you can sell the fenders and other parts to Stovebolters and make a few dollars! I've paid more than that for a truck and had to haul it home in pieces!! IF its as you say then don't let it get away....and if the guy wanted come down in buy it anyway. Don't let a few dollars stand in the way if you want the truck even if it means it has to sit a couple more months till you "replenish" your funds. Otherwise another one will be gone and the next one may not be so good!
