DiscoGreg, unfortunately it appears that none of the respondents so far have actually done a 1/4 chassis replacement. I have. (My company, Atlanta on Wheels, has renovated over 125 D2's, more than one with rusty frame rails). The job is not technically difficult, but a lot of work and does require a good MIG (or TIG) welder. Start by measuring and marking where the subframe will end its overlap of the truck frame. The measure back the distance of the overlap "sleeve" of the subframe (about 7 inches as I recall). Back that measurement up a 1/2 inch or so at that will be the cut point on the truck frame. Get close, but don't worry, this is not an exact fit job. Grind as much of the surface rust off the truck frame where that first mark was, that's where the weld must be good. But here's the hardest part: you are about to drop the gas tank and the cut-off section of the frame and every rusty nut an bolt will fight you and few will be reuseable after you've fought to get them off. So I strongly suggest you first get to an junkyard and find a not-so-rusty truck and snag the fuel tank mounts (bolts and straps, maybe the skid shield, too) and the rear frame mounting hardware. You may also want to swap out the tow hitch and its hardware. Next you are ready to drop the gas tank - it MUST come out for safety's sake! Refer to your RAVE manual for fuel pump removal; roll your cargo carpet up and remove the fuel pump inspection cover (again, you'll probably find the rust worms have been at work here too so it may be a good idea to snag the cover and screws from your junkyard find). Using a long drift and a 2 lb ballpeen hammer, work the FP retaining ring loose. This is slow, frustrating work, but it WILL go. Remove the fuel pump connections and set it aside. You won't need to mess with the fuel line, but it wouldn't be a bad idea to shield it with tinfoil or the like. Disconnect the filler hose (again, did you have good quality hardware?). Of course, you've planned for this event by driving as much gas out of the tank as you can beforehand. If you've gotten the good nuts and bolts you can use your cut-off tool to rip through the gas tank removal quickly, otherwise that's the battle Drop the tank. Fitting the subframe onto the chassis stubs will actually go pretty easy if you prepped the chassis well, but a big deadblow hammer and maybe a 3ft breaker bar should be at hand. Bolt the rear of the subframe in place and let your welder do his thing! He'll tack the subframe in place and then fill in the joint and the cutout corners of the subframe. . Maybe 3-4 hours for you and 1 for the welder. Hopefully your welder is a buddy...Good luck
