Somewhere there is an old school artical on not dropping the axle but moving it to the top of the spings
That doesn't work well on our old trucks where there is almost no room left between the axle and the frame. Also the way the axle is designed with the holes for the u-bolts in the upper edge its difficult to safely bolt the axle in place doing it that way.
And heating and stretching the axle is acually the 'old school' way to do it...