I found 3 12 bolt rear ends and several 71-72 10 bolt in a junkyard today. Would there be any advantages for the 12 bolt over the 10 bolt? There is only a $50 difference in price. The 12 bolts are in chevelles what is the best way to tell if they are in fact Chevy rear ends? What is a good price for a 12 bolt non posi?
The 12 bolts are a 8.875" rearend vs. the 10 bolts which are 8.5". Also, I believe the axles are 30 spline vs the 10 bolts 28 splines. Overall it's a stronger piece and parts are readily available. Stay away from the 8.2" 10 bolts as parts are not readily available new and are the weakest of the three.
Buy all 3 Chevy 12 bolts. You can easily sell them. A complete rear is going for $300. If posi, $600-700. You can also sell the 71-2 Skylark/Cutlass 8.5" rears. All depends on pricing.
Personally, I'd buy them all. Work a pkg deal & sell off what you don't need. Strength comparisons... Unless the 12 bolt Chevelle rears came out of '69 COPO Chevellesp , they are far from bulletproof. Generalizing that such a stock 12 bolt is stronger than a stock 8.5 bolt-in axle A-body does not take into consideration how weak most stock 12 bolt posi "Chevy" rears are. As an example, in a same weight A-body, the stock 28 spline axles in a '71-72 8.5 A-body rear will often hold up, where stock 30 spline "flared to spline" 12 bolt Chevelle axle rears will often twist an axle, or blow spider gears (stock Eaton 12 bolt posi carrier). In 3600-3800 lb A-bodys at the track on slicks, many many 1.60 & even mid 1.50 60 foot times have been recorded on stock bolt-in 8.5 A-body axles (footbraked,auto trans). Personally don't recommend stock axles at that point, but I can point out many successful street-strip cars that run them. Stock 12 bolt axles often need replacing... Buying a "Chevelle" 12 bolt & being able to install a posi unit & immediately run the stock axles that came with it is often a moot point. For the last 15 years, the vast majority of the GM c-clip 12 bolts, I've bought as cores needed new axles. Their c-clip axles were either chewed or pitted in the bearing lands & had to be replaced (can't recommend axle saver bearings). Yes, I've taken tons of damaged disassembled 12 bolts in on trades, but the trend of worn out c-clip axles was 1st recognized when pulling 12 bolt rears out of partscars & yardcars, not customer traded in rears in poor condition. Yarding... When buying "Chevy" 12 bolts, or c-clip 8.5 10 bolts, if nothing else than to help lighten the load, remove the rear cover, drain the grease, drop the c-clips, pull the axles, & examine the bearing lands on the axles. On such pegleg 12bolts, many times, one is just buying a 12 bolt housing, a set of 2.73's or 3.07's, & a chunkable pegleg carrier. Pointing out junk axles, often gives one a negotiating chip on price Hope this helps. Roger
