TommySS454 Posted December 31, 2019 Share Posted December 31, 2019 I know this isn't the correct rear end for my car, but can anyone identify it? It's a 12 bolt. Here's the tube stamp. Thanks Quote Link to comment Share on other sites More sharing options...
Paul Bell Posted December 31, 2019 Share Posted December 31, 2019 No Chevelle ever had a rear with the "RC" code. Can you tell us any more? What year do you think it is? Can we see more pics, including the cover? The 0515 is a date code but it's meaning changed through the years. Quote Link to comment Share on other sites More sharing options...
LS5 Posted January 1, 2020 Share Posted January 1, 2020 All I can find is that its an Olds diff with 3:08's inside. Oldsmobile delta 88's or the Jetstar..as far as thew RC code goes. the 05 15K would think its the 15th of November but the 05 is weird... Darren Quote Link to comment Share on other sites More sharing options...
Paul Bell Posted January 1, 2020 Share Posted January 1, 2020 Yeah Darren, I saw that code in Olds lists that's why I wanna see the cover. Quote Link to comment Share on other sites More sharing options...
TommySS454 Posted January 1, 2020 Author Share Posted January 1, 2020 Don't have a close up picture of the cover but I will attach a pic that you can zoom in to it. Looks like an ordinary 12 to me. All I will say is I put this rear end in after the previous one wore the trailing arm bolt holes to a nice oval shape. It wasn't the factory unit either. But my dad owned a salvage yard so this was already pulled out. I walked over to a selection of 12 bolts and picked one that was maybe a dozen years ago. Thanks for the replies. Quote Link to comment Share on other sites More sharing options...
Paul Bell Posted January 1, 2020 Share Posted January 1, 2020 Well that's definitely a Chevy car 12 bolt rear. Truck 12 bolts had a different cover. Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted January 1, 2020 Share Posted January 1, 2020 Also the Oldsmobile 12 bolt has a different cover. Quote Link to comment Share on other sites More sharing options...
TommySS454 Posted January 1, 2020 Author Share Posted January 1, 2020 I wasn't having luck finding anything online, that's why I posted here. Thought maybe I was a moron and wasn't looking it up right. Quote Link to comment Share on other sites More sharing options...
Paul Bell Posted January 1, 2020 Share Posted January 1, 2020 I'm working on it, it's a good challenge. Quote Link to comment Share on other sites More sharing options...
Paul Bell Posted January 1, 2020 Share Posted January 1, 2020 From the "K", I can say this rear was manufactured by McKinnon Industries. Tommy, see if you can get the casting number. It's on the front webbing of the cast center section. Quote Link to comment Share on other sites More sharing options...
TommySS454 Posted January 1, 2020 Author Share Posted January 1, 2020 I have it written down at home. I'll get it in the morning. My vision is fixing to get blurry. Quote Link to comment Share on other sites More sharing options...
jft69z Posted January 1, 2020 Share Posted January 1, 2020 May sound stupid, but what if the guy on the line stamped it backwards? "CR" would be a 3.07 posi according to a couple of lists out there. Quote Link to comment Share on other sites More sharing options...
Paul Bell Posted January 1, 2020 Share Posted January 1, 2020 That could be Joe. Tommy, while you're at it, measure how wide it is from axle flange face to axle flange face. Here's some numbers: Widths: 1964 - 1967: 60.5 inches 1968 - 1972: 61.25 inches Casting numbers found to be the most prevalent in Chevelle 12-bolt rear ends: 1965 Chevelle 3859140N 1966 Chevelle 3875745N 1967 Chevelle 3894939NF 68-69 Chevelle 3917124NF 1969 Chevelle 3959038NF 70-72 Chevelle 3969278NF Quote Link to comment Share on other sites More sharing options...
TommySS454 Posted January 1, 2020 Author Share Posted January 1, 2020 I haven't pulled the wheels off to measure yet. But the casting # is. 3917124N. Quote Link to comment Share on other sites More sharing options...
TommySS454 Posted January 1, 2020 Author Share Posted January 1, 2020 Pulled the cover and it appears to be a 3.07 ratio. 14 pinion teeth and 43 ring teeth. Quote Link to comment Share on other sites More sharing options...
Paul Bell Posted January 1, 2020 Share Posted January 1, 2020 OK, I'm gonna go with what Joe said, that the stamper got the letters swapped when he stamped it. The "CR" code would be a 1968 rear with the 3:07 ratio and the casting number. It should measure 61.21 inches. Quote Link to comment Share on other sites More sharing options...
TommySS454 Posted January 1, 2020 Author Share Posted January 1, 2020 That would make sense. It's not the first time I've seen old G.M. stuff with funky numbers. Thanks for the research everyone. Quote Link to comment Share on other sites More sharing options...
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