Not sure if I'd call it shrinking as much as beating it into submission. I was using my highly technical piece of railroad track as a dolly and mostly hammering on or close to it. It actually stretched the metal in some areas, but the end result came out ok.
Again, I don't really know what I'm doing, but since this is old rusty junk I figured I would give it a shot. Plus it's just a truck bed floor. What's the worst that could happen, right??
I did do a more detailed thread on this, maybe it can be a bit more helpful
http://67-72chevytrucks.com/vboard/s...d.php?t=739356
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ClusterTruck: 68 C10 Bought in 89, wrecked in 03. Slow low $ rebuild started '17. 6.0 & TKO
http://67-72chevytrucks.com/vboard/s...d.php?t=788602
93 K1500 Short Step, 350, NV4500, EBL flash ECU. Vortec heads & roller cam someday...
05 Jeep Wrangler Unlimited. 3” lift & 6-speed
02 E320 the insurance total “free car”
13 Tahoe LTZ