The 2wd S10 rear end is 54-3/8" from wheel mounting surface to wheel mounting surface. The 4wd rear end is 4" wider (wms) or about 58-3/8".
Its a 10 bolt axle with 7.50 ring gear, 28 spline axles.

1951 Ply Concord truck
1954 Nash Rambler 2 dr
1955 Nash Rambler Farina