The chain and bottle jack that Jerry has used can work, but in order to get the end of the axle bent downward, you'll be pushing on the high point of the arc of the bent axle, and the safest way to do it is with the axle in the truck. If the axle is loose, it's very possible that it will flip over when pressure is applied and cause injury to equipment or you. If doing it yourself, I wouldn't depend on a magnetic angle finder as you need to have both ends the same. A more precise method like measurements from a baseline (your support beam) would be better. AND you have to check that the axle isn't twisted as well as the end bent up. Here's a crude diagram for bending to get more camber. To get less camber you'd need to swap the jack and the outboard chain.
If it were me, I'd let a truck shop handle it. I once had a rear axle straightened but they messed it up. It was straight at the ends but the center housing was still angled and it eventually killed the differential because the limited slip disks started shucking the petals off into the pinion bearing. Not pretty,
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
