Rear end gears for 94 chevy

[rchavez101]

Hey guys can you tell most likely what rearend gears I would have in my 94 chevy 2wd with a 4.3 liter? I am getting ready to order a 700r4 transmission and they would like to know what rear end I have in the truck. I know I can take the rear diff cover off and it should be stamped on the gears. Or at least I think it should. It's the stock gears. I don't have the codes in the glove box that would tell me what it is. Thanks

[sntrym95]

My old 94 had 3.42's with the 4.3 liter. You can always tell by lifting the rear, spin a tire, and count the rotations of the drive shaft. Marking the shaft helps.
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[rchavez101]

Originally Posted by sntrym95

My old 94 had 3.42's with the 4.3 liter. You can always tell by lifting the rear, spin a tire, and count the rotations of the drive shaft. Marking the shaft helps.
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Thanks Mike. So If it is correct I should see the driveline rotate about 3 1/2 times for one rotation of the wheel?
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[gregory5000]

You can also look in the glove box and write the codes down and then decode them. They are RPO codes, just search that for GM. If you know the history of the truck this works, someone could have changed the rear too.

[rchavez101]

Originally Posted by gregory5000

You can also look in the glove box and write the codes down and then decode them. They are RPO codes, just search that for GM. If you know the history of the truck this works, someone could have changed the rear too.

The codes are worn out.
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[dragginmetal]

IMO, if your ordering a 700r4 transmission. It's worth the price of a gasket and some gear oil to be 100% sure. It should be stamped on the gears. I have two rear ends here and they are both stamped on the gears.

[gregory5000]

Originally Posted by rchavez101

The codes are worn out.
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Take your vin to the dealer can they can tell you what the codes are.

[Mark S]

Originally Posted by rchavez101

Thanks Mike. So If it is correct I should see the driveline rotate about 3 1/2 times for one rotation of the wheel?
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rchavez, if your's is an open rearend (non-posi) you can lift one wheel, rotate that wheel exactly two times and count the number of revolutions of the driveshaft. The reason for two turns is the driveshaft revolutions are reduced 50 percent through the spider gears when turning ONE wheel. If you have a posi and it doesn't cooperate, lift both wheels and rotate both wheels exactly one time and count the number of revolutions of the driveshaft. About 3 1/2 turns will be a 3.42.
Good Luck, Mark

[dragginmetal]

Originally Posted by Mark S

rchavez, if your's is an open rearend (non-posi) you can lift one wheel, rotate that wheel exactly two times and count the number of revolutions of the driveshaft. The reason for two turns is the driveshaft revolutions are reduced 50 percent through the spider gears when turning ONE wheel. If you have a posi and it doesn't cooperate, lift both wheels and rotate both wheels exactly one time and count the number of revolutions of the driveshaft. About 3 1/2 turns will be a 3.42.
Good Luck, Mark

Mark, What if the tires are shorter or taller than stock. Woudn't that make the driveshaft turn less or more? If one full turn on a 28.5" tire makes 3 1/2 turns, then if it were a 26" tire wouldn't the driveshaft turn less then 3 1/2 turns? Or am i thinking all wrong on this?

[mrdana60]

My 94 with the 4.3 and auto has 3.08 gears. I ve wanted to go to 3.42 or 3.73

[Boog]

Originally Posted by dragginmetal

Mark, What if the tires are shorter or taller than stock. Woudn't that make the driveshaft turn less or more? If one full turn on a 28.5" tire makes 3 1/2 turns, then if it were a 26" tire wouldn't the driveshaft turn less then 3 1/2 turns? Or am i thinking all wrong on this?

One full turn is one full turn regardless of the tire diameter.

[dragginmetal]

Originally Posted by Boog

One full turn is one full turn regardless of the tire diameter.

Ok thanks. I don't know to much about trans and rear end gearing. Figured it must have been a dumb question since no one wanted to touch it.

[Mark S]

Mike, Been away from the computer, work has been brutal. Boog is right, tire size does not change gear ratio. It does change FINAL drive ratio. That is to say, different size tires will affect your speedometer reading. Larger tires will cause your speedo to read slower than actual speed. Smaller tires and it reads faster. Something to keep in mind.
Good Luck, Mark

[ChevLoRay]

There's a website that has been posted on here in the past, that allows you to input your VIN and it will tell you things about that vehicle. What I don't remember is whether or not it will also list what is on your SPID...or the sticker that refers to what your vehicle left with from the factory. Seems like it was www.compnine.com.

Yep, that's it. Give it a try.

[project 67 sub]

checked mine on that site, and that all sounds/looks correct to what mine was originally EXCEPT the body color was not the smoke metallic color that it says it was, it was that aqua green color, interior color is correct as well (dark red/burgandy)
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[dragginmetal]

Originally Posted by Mark S

Mike, Been away from the computer, work has been brutal. Boog is right, tire size does not change gear ratio. It does change FINAL drive ratio. That is to say, different size tires will affect your speedometer reading. Larger tires will cause your speedo to read slower than actual speed. Smaller tires and it reads faster. Something to keep in mind.
Good Luck, Mark

Thanks Mark. I was thinking about final drive ratio. Thats were i got confused. I knew tire size affected this and was thinking it affected the rearend. You and Boog got me strait. I understand now.

[85extendedcab]

Hey guys, ive got a 69'short stepper with 350/350. Either my 3rd gear is goin out or
My rear is geared high. My son and I tried the lift and spin tire trick.. we rotated my non posi rear end while in neutral, and after 1 spin the driveline rotated 3 full times.. Anybody know what gear that would be? Any help appreciated, Jason
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[Mark S]

Jason, sounds like a 3.08
Mark