This is supposedly out of a 70's GM car, but I can't find this code listed anywhere! Any help appreciated
https://www.speedwaymotors.com/GM-1...h-Ring-Gear-Rear-End-Diff-Axle-Cover,711.html The cover plate appears to be aftermarket and fits GM 10 bolt with 8.2" and 8.5" ring gears.
What is the exact code you can see? It is a little hard to read the 2nd and 3rd characters in the pic. https://www.chevyhardcore.com/tech-stories/drivetrain/10-bolt-chevy/ Manufactured at the Buffalo plant - August 15th........??????
That is the only picture of the code number from the ad. It looks like CC ?227. I can't make out the 3rd character
This is from the link above. Looks like a GM 8.5" 10 bolt. It has the square lugs at 5 and 7 o'clock. Most 8.5-inch 10-bolt rearends have two extruded, cast-in lugs on the bottom of the differential housing at the 5:00 and 7:00 positions. The covers on the 8.5-inch rearends are often 11 inches round with a bulge on the driver’s side to accommodate the ring gear. The distance between the lower center bolt on the cover and either adjacent bolt is 3 3/4 inches. The OEM pinion nut is 1 1/4 inches.
It looks like it is a 8.5" 10 bolt by the square lower lugs on the center section. The CC at the start of the stamped code points towards it being a 2.73 limited slip. There should then be another letter to identify the manufacturing plant. Can't tell if it is there in the pics. The 227 is the numerical day of the year it was made, and is August 15. Further along there should be another number to identify day or night shift (1 or 2). This is out of shot in the pic. This is good info. Look for CC in the right hand column.....(1973 and 1974 A & G bodies) http://www.wallaceracing.com/axledata2.htm @squirrel may be of great help with this.
If I remember correctly, the CC is the ratio code. CC is 2.73:1. It may or may not have a Positraction carrier, but it likely does not. It was less common option then. Ratio: CC Plant: (unreadable) Assembly Plant. Likely Buffalo - C, or Detriot Gear & Axle - G, or Oldsmobile - O based on the shape. Digits: Julian date of the production year. 227th day of the year. August 15th, or August 14th if a leap rear. There should be another digit indicating shift, but it is missing (not unusual).
Well, It definitely deserves looking at. It's pretty easy to determine if its an open carrier or a posi unit. Looks to be in decent condition too. Wish me luck
As far as I can see, the CC code on an 8.5" denotes 2.73 as a limited slip. An open center 2.73 would have an AC code. Of course, anything could have been replaced or changed since the 70's.
Well, I own it now! Went to look at it and it looked nice and clean inside, no metal floating around and gears looked perfect and oil was clean. It has one axle bearing that felt slightly loose and has no brake hardware at all with it, just backing plates, but I have a donor 8.5" open carrier rear end that has everything. Easy to swap parts over. Got it for $200
It will be going under my 47 Olds coupe. I'll leave it as is for now, but it is the right carrier if I want to go with a steeper gear later on. I think I did pretty good, nice inexpensive posi. Those 2 words don't usually go together anymore!
Don't know for sure yet, but it moves nice and smooth. I'm going to have to get into a little bit to check things out a little more before I know if it's as good as it appears. Edit: I'm not an expert on posi's, but I'm sure there are plenty here that could help if I find issues.
Generally those mid-70's 2.73 and 3.08 ratio posi rears weren't worked all that hard in their life, since nothing in that era made any real HP. So if it hasn't been in a car hotrodded for part of its life and just served general passenger daily duty the posi will be almost like new. $200 is a really good score in this day and age.
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