Packratt Posted April 11, 2021 Share Posted April 11, 2021 I’m looking up parts to convert my 2:73 open to a 3:36 or 3:55 posi rear. In my research I found Yukon carriers are made in China and Eaton Tru-Trac is made in Tiwan while Auburn Gear is supposed to be made in the USA. Are there any other American made carriers that you know of. I’m just trying to support our American workers while rebuilding my American car. Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted April 11, 2021 Share Posted April 11, 2021 Sorry, I agree with you thoughts but you can't beat a trutrac. So simple and so strong! I have broken to bits every posi you mentioned plus a moroso "brute strength" posi and a strange posi. Believe me on this one, purchase the trutrac and you can thank me later. No clutches, no special additives, just simplicity that works. 2 Quote Link to comment Share on other sites More sharing options...
714024SPEED Posted April 11, 2021 Share Posted April 11, 2021 I've seen the carnage of all of Toms Posi explosions ,go with the Tru trac . It's the only one to hold up ......so far 2 Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted April 11, 2021 Share Posted April 11, 2021 3.36? 3.55? 10 bolt? Still, trutrac! Quote Link to comment Share on other sites More sharing options...
70MC402 Posted April 11, 2021 Share Posted April 11, 2021 I bought a trutrac for my 12 bolt 3:73 conversion at the suggestion of MC1of80 on one if my threads from a few months ago and made in Taiwan or not it's a solid unit. 1 Quote Link to comment Share on other sites More sharing options...
Grant MacPherson Posted April 12, 2021 Share Posted April 12, 2021 I spoke to a builder/racer and he said for street use go with a 3:42, he said every 3:73 he put in customer complains about highway RPM. just my 2 cents worth. I still have the 2:56 open that I hate except on the highway, cruising at 90 and not even breathing hard. Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted April 13, 2021 Share Posted April 13, 2021 I have a 3.31 gear with detroit trutrac in my 496 70 SS Monte Carlo "Big Red" and the same exact rear in my 71 402 Monte Carlo "Barn Find" Big Red has seen more track time than street time. The 496 loves the 3.31s Quote Link to comment Share on other sites More sharing options...
70white402 Posted April 13, 2021 Share Posted April 13, 2021 I just put a tru track in my Monte with 3:73 but with the tremec 5 speed so the revs should be good at highway speed. It also has a 496 1 Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted April 13, 2021 Share Posted April 13, 2021 My 2010 Sierra daily driver even has a trutrac after I exploded the gov-lock factory junk. 1 Quote Link to comment Share on other sites More sharing options...
70white402 Posted April 13, 2021 Share Posted April 13, 2021 I put the tru trac in because of you. 1 Quote Link to comment Share on other sites More sharing options...
cny first gen 71 Posted April 13, 2021 Share Posted April 13, 2021 Sold me on the tru track when I get ready to do mine. Now I just gotta figure weather to stay with the 10 bolt original or do the 12 bolt I bought a couple years ago. Not going to have a real high horse power engine. I could probably sell the 12 bolt for enough to rebuild the 10 bolt. Decisions decisions Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted April 13, 2021 Share Posted April 13, 2021 Depends on which 10 bolt you have. If the 8.2, I would use the 12 bolt. If the 8.5, then the choice is yours. The 8.5 is just as strong when built as the 12 bolt. 1 Quote Link to comment Share on other sites More sharing options...
70MC402 Posted April 14, 2021 Share Posted April 14, 2021 On 4/12/2021 at 6:59 PM, Grant MacPherson said: I spoke to a builder/racer and he said for street use go with a 3:42, he said every 3:73 he put in customer complains about highway RPM. just my 2 cents worth. I still have the 2:56 open that I hate except on the highway, cruising at 90 and not even breathing hard. Im sure it's going to be quite a bit higher running but i still have 29 inch tall tires on mine and ive got a 4l80e i may end up installing if the RPM drives me nuts. I dont do much highway with it anyways, the roads i typically drive on are 55 mph roads. But thank you for rhe advice if I decide i cant stand it. Quote Link to comment Share on other sites More sharing options...
Grant MacPherson Posted April 14, 2021 Share Posted April 14, 2021 the 4180E has overdrive so that would fix the rpm problem Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted April 14, 2021 Share Posted April 14, 2021 With a 4L80e you will be fine with the 3.73. Quote Link to comment Share on other sites More sharing options...
jft69z Posted April 14, 2021 Share Posted April 14, 2021 I have 4.11 with a 4L85E and it's not too bad on the highway. Quote Link to comment Share on other sites More sharing options...
71MonteCarloMD Posted January 8, 2022 Share Posted January 8, 2022 Curious how do I know if I have 8.2 or 8.5 10 bolt? Am considering to replace on my 71 Monte and 72 C15 for better gas Quote Link to comment Share on other sites More sharing options...
cny first gen 71 Posted January 8, 2022 Share Posted January 8, 2022 21 minutes ago, 71MonteCarloMD said: Curious how do I know if I have 8.2 or 8.5 10 bolt? Am considering to replace on my 71 Monte and 72 C15 for better gas 4 Quote Link to comment Share on other sites More sharing options...
71MonteCarloMD Posted January 9, 2022 Share Posted January 9, 2022 Steve, thanks will check. I’m wondering if I have 8.5 as I can swap with 4L80E to get better gas? 1 Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted January 9, 2022 Share Posted January 9, 2022 Huh?!? The rear gear diameter, 8.2, 8.5, 8.75 (12 bolt) has nothing to do with gas milage. The gear ratio, 2.41, 2.56, 2.73, 3.31, 3.42, 3.73 etc does. So does the tire diameter, not width. Ie 26", 27,28, 30". Just for comparison, many will remember (lol) the 80s Monte Carlo SS, 442 and Hurst Olds? They had 3.73 gears and a 4spd overdrive and could be driven anywhere. The SS had a 7.5 rear (junk) and a 200r4 trans while the Olds had a 8.5 rear (stout) and also the 200r4 trans. Also the Grand Nationals and t-types had the 8.5 rear with a 3.42 ratio and the 200r4. All with roughly a 26.5-27 inch tall tire. And decentish gas milage. 1 Quote Link to comment Share on other sites More sharing options...
Dtret Posted January 9, 2022 Share Posted January 9, 2022 I feel offended. All I got out of that was that my 88 SS is junk. Lol. Jk. I put a gm zz4 crate in my 88. I’m waiting to see what is going to go first. The 200 r4 or the rearend. 1 Quote Link to comment Share on other sites More sharing options...
MC1of80 Posted January 9, 2022 Share Posted January 9, 2022 Sorry if you are offended. The rears in the Monte SS of that era, the 7.5 is junk. Especially if you use sticky tires. Traction kills the rears. Let it spin or boom! Lolol Get a Grand National it better yet, if you can find one 442/Hurst Olds 8.5 rear and driveshaft for when the 7.5 in the Monte gives up the ghost. The 442/Hurst Olds have 3.73 gears that match the Monte SS as opposed to the 3.42 in the GN. A 12 bolt, 68-72 a-body, will fit also with offset control arms. Idk if they make them anymore. We may have a set "in stock" but the 12 bolt is wider and different offset rims would be required. Quote Link to comment Share on other sites More sharing options...
Dtret Posted January 9, 2022 Share Posted January 9, 2022 10 minutes ago, MC1of80 said: Sorry if you are offended. The rears in the Monte SS of that era, the 7.5 is junk. Especially if you use sticky tires. Traction kills the rears. Let it spin or boom! Lolol Get a Grand National it better yet, if you can find one 442/Hurst Olds 8.5 rear and driveshaft for when the 7.5 in the Monte gives up the ghost. The 442/Hurst Olds have 3.73 gears that match the Monte SS as opposed to the 3.42 in the GN. A 12 bolt, 68-72 a-body, will fit also with offset control arms. Idk if they make them anymore. We may have a set "in stock" but the 12 bolt is wider and different offset rims would be required. Not offended at all. I know it’s only a matter of time. Lol. Boom. I’m walking. Good thing I have AAA. Lol. Now I’m going to go shopping. 1 Quote Link to comment Share on other sites More sharing options...
Scott S. Posted January 9, 2022 Share Posted January 9, 2022 Tough call on which will go first. Funny how the Montes of the late '80's were the weakest of the four "A" bodies. I had an '86 Buick T Type, with the 200r4 and 3.42 gears, and the transmission started to let go around 200,000 km's. I found out at the rebuild that Buick's version of the 2004r is unique to the car, G.N.'s and T Types, and the Montes were the last to go with 200r4s. seems almost like G.M. didn't really want to put them in there.... My cousin had an '85 SS, but it was the 305ci engine that let go first. Mind you, he was still running a th350 transmission. Quote Link to comment Share on other sites More sharing options...
71MonteCarloMD Posted January 9, 2022 Share Posted January 9, 2022 17 hours ago, MC1of80 said: Huh?!? The rear gear diameter, 8.2, 8.5, 8.75 (12 bolt) has nothing to do with gas milage. Forgive my ignorance Tom! I was just wondering what I can do to get a better mileage. Quote Link to comment Share on other sites More sharing options...
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