Posted 18 September 2009 - 06:59 AM
I repaired some cracks in my 99 2500 fleetside bed last yr. I had made a saddle rack that clamped under the edge of the top lip of the bed and had a brace that angled inward and down to the corner formed by the bed and inside wall. This formed kind of a triangle and was pretty strong to set a 50-60lb saddle on. The load path was pushing down on the down and inward angled brace, but it was also pulling the inside upper lip of the bed in toward the center of the bed.
Over time, the loads from the saddle broke the upper lip in a few places and even separated a few spot welds where the inner and outer bed skins joined. The inner bed skin had some 5-6" cracks downward and the outter skin had some cracks over the bed rail and down to the tailight and actually running along the tailight.
I ground off the paint and TIG welded all the cracks and seams back together. Well technically, I watched my friend's shop workers do this. They thought about MIG welding (they have oyx-acetylene, TIG and MIG) but decided there was better control with TIG. Then I ground them down flush on the areas that show with a little 2" disk sander. I sprayed primer on them and haven't gone further with fill and paint.
Let me put my two cents in about the welding. I don't beleive any of the three types of welding I mentioned above are wrong. They all offer their own characteristics in ease of use and results. TIG offers much more control over MIG. MIG is fast and its the bodyshop method of choice. But, MIG can be difficult and sloppy for a small job. Oxy-acetylene gas welding can be used for most stuff and is easy, but can be slow and introduce a lot of heat over a long period of time into the part being welded.
2008 Silverado 1500 VMax Crew 4x4 LTZ, NHT (L76 6.0L, G80, 4.10, Z85, 7300 lb GVWR) Victory Red/Ebony leather, Blackbear custom tune, Bilstein 5100 adjustable ride height front shocks (leveling), rear Bilstein 5100 shocks, HID Fogs, H-9 mod Lo-beams, SSU Hi-beams, SnugTop SuperSport, GMC Sierra 6 spoke wheels, 285-70/17 LR E Toyo Open Country A/T, Hellwig rear swaybar .
1999 1/2 Sierra 2500 SLE Extcab 4x4 6.0L all stock w/265-75/16 Firestone M/T (gone)
1998 2500 4wd extcab 350 ci (gone now, chevy buyback on lemon law)
1979 GMC El Camino 400 ci smallblock, 2.02 heads, cam, headers, Edelbrock,etc, 400 (HD truck) Hydra-matic swap, blueprinted, clutchpack, hi stall converter. (gone now)