Scott S. Posted April 17, 2021 Share Posted April 17, 2021 I'm wondering what some of the issues I'll run into if I replace the 10 bolt differential in a 1970 Monte with a 12 bolt differential from a 1972 El Camino. ie, U-joint, drive shaft length, shock and control arm differences... etc. Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted April 18, 2021 Share Posted April 18, 2021 Best case scenario you will need a "combo" u-joint. From the 10 bolt big cap to the 12 bolt small cap. Some find it necessary to cut the 10 bolt driveshaft or replace it. If the car is a 10 bolt but has a th400 in it, the combo joint is all you will need. But most small block equiped Monte Carlos were th350s. Everything else is the same. Quote Link to comment Share on other sites More sharing options...
Scott S. Posted April 18, 2021 Author Share Posted April 18, 2021 Hey MC, Thanks for the response..... It's an original '70 350/th350 car, but I've replaced the transmission with a re-worked 200r4. She's an "end of year run" car, and I've noticed a few '71 bit and pieces here and there. The one puzzling me is that the differential yoke uses the U-bolt straps instead of the usual mini U-bolts to hold the joint in place. Is this due to a different cap size ?? Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted April 19, 2021 Share Posted April 19, 2021 The 200r4 is the same length as the th350 and uses the same yoke. Your factory driveshaft probably slipped right in. Not sure about the strap vs the u bolts . I have had both on 10bolts. The 12 bolts usually have the straps. Quote Link to comment Share on other sites More sharing options...
714024SPEED Posted April 20, 2021 Share Posted April 20, 2021 Here is the u joint part number you will need to do the swap 1 Quote Link to comment Share on other sites More sharing options...
Scott S. Posted April 20, 2021 Author Share Posted April 20, 2021 Thanks for the information..... I kept coming up with Moog 348, but it didn't seem right. Quote Link to comment Share on other sites More sharing options...
70MC402 Posted May 27, 2021 Share Posted May 27, 2021 Sorry im not adding any informative value im just here to say that green looks kick**s on your Monte. I feel like greens are typically overlooked and undervalued. Nice car man. Quote Link to comment Share on other sites More sharing options...
MC-71 Posted May 27, 2021 Share Posted May 27, 2021 I remember back then that GM used some rears that went in Buick’s. There was a shortage. I know my friend has that same rear in his 70 Monte. Clips instead of bolts. Quote Link to comment Share on other sites More sharing options...
Scott S. Posted June 3, 2021 Author Share Posted June 3, 2021 On 5/26/2021 at 10:32 PM, 70MC402 said: Sorry im not adding any informative value im just here to say that green looks kick**s on your Monte. I feel like greens are typically overlooked and undervalued. Nice car man. No problem !!!! And Thanks !!! I bought her mainly because of the colour...... Almost every other one I looked at was either black or blue with the vinyl top. Sadly, sort of, I got caught in a hailstorm last summer, and she took a beating............ But my buddy owns a body shop and he's going to match the colour. The good part is that having the body re done, a lot of flaws in the previous attempt have been revealed, (and there were lots !!) and the insurance is more than enough to cover it. It's just that I'm going crazy not having her to drive now that summer's here.... :( Quote Link to comment Share on other sites More sharing options...
Scott S. Posted June 3, 2021 Author Share Posted June 3, 2021 On 5/27/2021 at 7:42 AM, MC-71 said: I remember back then that GM used some rears that went in Buick’s. There was a shortage. I know my friend has that same rear in his 70 Monte. Clips instead of bolts. The BOP parts.... lol I haven't really found an I.D. numbers on it to tell, but being a "end of year run" car, it could be quite possible. Thanks. Scott. Quote Link to comment Share on other sites More sharing options...
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