Rear End Gears
Rear End Gears I heard that it says what gears are in your rear end on the sticker in the glove box can someone explain where and what the codes are for the differant ratios thanks.
TECH Senior Member
iTrader: (3)
Joined: Oct 2006
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From: Decatur, TN (N-W of Athens)
Yes. The "G" RPO code is the reference to your gear ratio. Mine, GU5 is 3.23. I now have GU6, which is 3.42s (changed rear ends due to accident). I would just take a picture, or copy them allllll down and then check them out at this site. It's fun to see what your car has 
http://www.crankshaftcoalition.com/w...e_GM_RPO_codes
My friends S-10 he picked up that we're small blocking, has GT5. 4.10s BABY! lol
http://www.crankshaftcoalition.com/w...e_GM_RPO_codes
My friends S-10 he picked up that we're small blocking, has GT5. 4.10s BABY! lol
Launching!
Joined: Feb 2006
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From: South Carolina
^^if you're gonna change 'em out i would definitely go with an aftermarket gear. 3.73 is always good, but everyone has a different opinion on that. if you're going to pay to have them put in though i wouldn't replace them with another factory gear ratio.
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On The Tree
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I just changed my 1994 Z28 with 4L60 A4 tranny from 2.73 to 3.42's. Love the difference. I was advised to go to 3.73 but I'm glad I didn't. It's a street car and the 20% jump in RPM per MPH worked out perfect. Get up and go , but it still cruises great at higher speeds. Did not see what year car or tranny you are running you're speedo will be off, and if its and automatic the the 2>3 upshift at WOT may hit the rev limiter prior to shifting. The old 93 MPH shift point may now take you well over 6000 RPM. I had to fix mine up with TunerCat , none of the local shops including a couple of dealers knew how to alter the old ODB1 PCM.
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TECH Senior Member
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From: Decatur, TN (N-W of Athens)
Bob, you have a 4L60E btw, I have the 4L60.
If you change Rouda, you're going to need the carrier too, unless you get aftermarket ones made for yours. 2.73 uses a different style than 3.23+ cars. So you can't just toss in the gears. I would get the 3.42s out of a car with the carrier. Any M6 car will have them and 93-02 all work. 99+ has better posi unit, it's what I have now.
If you change Rouda, you're going to need the carrier too, unless you get aftermarket ones made for yours. 2.73 uses a different style than 3.23+ cars. So you can't just toss in the gears. I would get the 3.42s out of a car with the carrier. Any M6 car will have them and 93-02 all work. 99+ has better posi unit, it's what I have now.
Teching In
Joined: Oct 2005
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take a look a ebay for a whole rear end setup out of a m6 car. I found one with only 67000 miles on it for $100. i love my 3.42's, big increase from my 2.73's. But if its not a DD, i would definitely look at 3.73's
I would imagine the gears would work, but spending the money to all new bearings and seals and the cost of getting them installed def. wouldnt be worth it IMO. Grab urself a set of Richmond 3:73 and get someone that knows what they are doing and takes their time to install them. You will be spending an extra 150.00 bucks or so for the gears, but it will be worth it, and you will be much happier. I doubt you will notice a real big difference from 2:73 to 3:23. I would stay away from anything GM as far as a performance application goes. Metal gets thinner as the ratio's go up, so id stick with a brand that is known for strength ie Richmond. 
On The Tree
Joined: Nov 2007
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As far as a gear change.. unless you are experienced and have the tools to do it yourself it's going to cost $300-400.00 to have the work done. So you may as well go the extra $150-200.00 and get a new set. My 94 Z28 4L60e A4's rear has a Series 2 carrier. The shop installed an OEM Series 3, 3.42 set with a series 2 adapter kit, after multiple tries they could not eliminate a cruising whine ?? They finally took them out, installed Richmond 3.42's made specifically for the GM Series 2 carrier and it adjusted up first try. The whole experience took two days and multiple tear downs between test drives. It ended up OK but had me worried for a while.
