ThirdMC Posted August 13, 2011 Share Posted August 13, 2011 How many different 10 bolt rearends came in the FGMC? Is it just a mixture of 8.5 and 8.2? Too much rust on my axle tubes to find the code but according to my build sheet I have the GS1 2:73 ratio axle. Engine (*L65 350 CID 2-BBL) Transmission (=M38 3 SPD CBC) I can decipher some of this but don't know what all of it means for sure. I would like to put a little lower gears in it eventually and would like to know exactly what type/kind to order. Quote Link to comment Share on other sites More sharing options...
Archie Posted August 13, 2011 Share Posted August 13, 2011 Look down at post #15, there is a pic that shows how to tell the different 10 bolts a part. http://www.chevelles.com/forums/showthread.php?t=349703&highlight=10%2Bbolt Quote Link to comment Share on other sites More sharing options...
Archie Posted August 13, 2011 Share Posted August 13, 2011 8.5" 10 bolt or 12 bolt are the most desirable if you are making some good power and going to make a few track runs with slicks. With your motor and it sounds like you just want to wake it up some for a little more fun on the street you're fine just getting some gears and a posi with the 8.2" that is most likely in your Monte. At least my 10 bolt is the 8.2" in my 1972. A recommendation for gears would be richmond or motive, I have had success with both. On the chevelle board it sounds like many are having good luck with yukon stuff as well. Quote Link to comment Share on other sites More sharing options...
ThirdMC Posted August 14, 2011 Author Share Posted August 14, 2011 Mine doesnt have the 'lugs' on the bottom like an 8.5 but, it also doesn't have the obvious diagonal indentation on the cover like the 8.2. Is there another way to tell? Quote Link to comment Share on other sites More sharing options...
Monte7071 Posted August 15, 2011 Share Posted August 15, 2011 Post a picture it could be a BOP 8.2 or a BOP 12 bolt things get changed over the years. I had a 70 that had a 67 Chevelle 12 bolt in it. Quote Link to comment Share on other sites More sharing options...
ThirdMC Posted August 16, 2011 Author Share Posted August 16, 2011 Have a picture on my iphone but can't figure out how to get it to load. Quote Link to comment Share on other sites More sharing options...
Monte7071 Posted August 16, 2011 Share Posted August 16, 2011 I had a 70 Monte that had a BOP 10 bolt they have athe scallops on both sides of the center section where the axle tubes are. Early 8.2 Chevys had a cover like a 12 bolt chevy. The later 8.2 and 8.5 chevy is very similar. The best way to be sure is to pull the cover and measure it and look for a part number on the ring gear. Try this site to see if it helps BOP link Here is a pic of a BOP 12 bolt Quote Link to comment Share on other sites More sharing options...
Monte7071 Posted August 16, 2011 Share Posted August 16, 2011 Go to this site he is a member I think he goes by Monzaz he knows what he is talking about. link Quote Link to comment Share on other sites More sharing options...
ThirdMC Posted August 17, 2011 Author Share Posted August 17, 2011 A little more info: Rearend code: CGC 173 2 (2.73 Gears, Built in Buffalo on the 173rd day of the year, 2nd shift,No Posi) It has bolts and straps instead of u-bolts holding the yoke. It has what looks like E 111 or something like that stamped on the lower right side of the housing. As I mentioned before it doesn't have the lugs below the cover like the photo of the 8.5. What it does have is two small nothches in the housing at about the 5 & 7 o'clock positions. About where the 'lugs' are on the 8.5. Quote Link to comment Share on other sites More sharing options...
Archie Posted August 17, 2011 Share Posted August 17, 2011 That looks like an 8.5". Where the axle tubes join the backing plates do they tapper a bit (the axle tube)? Quote Link to comment Share on other sites More sharing options...
ThirdMC Posted August 17, 2011 Author Share Posted August 17, 2011 Yes Sir, the axle tubes taper a little about 1/4 - 1/2 inch before it meets the backing plates. Quote Link to comment Share on other sites More sharing options...
cbolt Posted August 17, 2011 Share Posted August 17, 2011 Mine is almost identical, but is a GCC I think and 135 2 with the two indentations at the 5 and 7 oclock positions. Quote Link to comment Share on other sites More sharing options...
Archie Posted August 19, 2011 Share Posted August 19, 2011 Yes Sir, the axle tubes taper a little about 1/4 - 1/2 inch before it meets the backing plates. Then I would say that is the chevy 8.5". That rearend is good rearend to put money into. Not worth trying to find a 12 bolt. Quote Link to comment Share on other sites More sharing options...
ThirdMC Posted August 20, 2011 Author Share Posted August 20, 2011 Checked the size of my pinion nut today and it's 1 1/8 so, I guess mine is the 8.2. Quote Link to comment Share on other sites More sharing options...
cbolt Posted August 20, 2011 Share Posted August 20, 2011 Did the same this morning, 1-1/8 pinion nut. Quote Link to comment Share on other sites More sharing options...
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