This 28 page Chevrolet Service Manual dated June 1957, covers the field installation for Posi Traction Rear End and Axel Overhaul for 1955, 1956, and 1957 Chevrolet & Corvette (and would cover newer years also) The overhaul section includes Disassembly, Cleaning and Inspection, Assembly and Adjustments, it tells how to determine correct thickness of Pinion Depth Shim to be used in front of Rear Pinion Bearing also., it also gives helpful tips on installing the positraction unit in non posi rear end housings. All the Information you need to Completely Overhaul and Rebuild this Rear End yourself.