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chevjayfsd · 11-22-2002, 03:35 PM

I have a 12 bolt, and i am going to get some 3.73's soon..What all do i need to get for the 3.73's to get posi in it?? is it just the carrier to change or what??
Thanks
Jason

**1971Stepside** · 11-22-2002, 03:55 PM

Straight from my Randy's Ring and Pinion invoice:

1. YG GM12T-373 Ring and Pinion......149.99
2. AK 1559 Axle Bearing and Seal Kit......29.50
3. EAT19556 12T 3.73 HD Posi, Complete 30spl....340.00
4. YKGM12T 12 bolt GM Truck Install Kit. Includes shims, crush sleeve, carrier bearings, etc................83.36
5. SVOM19519546A Positraction Additive.........3.00
6. 2 Quarts of 80-90 weight gear oil.......8.00 (I bought this local)

There you go. Dig into the penny bank and go for it. I got mine set up by a pro for $70.00. I think I have around 584.00 in the whole thing. The rearend was out of my truck and fully disassembled.

c10crazy · 11-22-2002, 04:05 PM

You mean $684, right?. How much difference did it make?.

Alexis · 11-22-2002, 04:19 PM

didn't someone post that if the 12-bolt didn't come with posi or somthing from the factory, that you couldn't swap in a posi cause of the size of the diff. inside.

**1971Stepside** · 11-22-2002, 04:19 PM

No, the price I showed on the posi is what they advertise the thing for. I got it for considerably less (270), but I don't want to put them in a bind on that price and be "false advertising" for them. I found the posi for 280 at tom differential and they beat it.

As far as performance it will be another year and a half before I know. I am doing a full frame up on the truck.

crazy longhorn · 11-22-2002, 04:37 PM

Alexis, you can swap a posi unit in where ther was an open carrier. You just need to have the proper series carrier for the gear set that you chose. 3.73 is on a 4 series carrier....3.73,4.10,4.56 ect. The 3.07 is on a 3 series carrier(3.07-3.42), So to change from a 3.07 gear to a 3.73, you will also need a carrier change to a 4 series. ......the housings are all the same (12 bolt), with the exception of the tube widths on different yrs......crazy AL

Alexis · 11-22-2002, 05:07 PM

thanks crazy longhorn...........always good to clear up info.

11-22-2002, 03:35 PM	#1
chevjayfsd Project 7dos Join Date: Aug 2001 Location: Abilene, Texas Posts: 876	What is needed I have a 12 bolt, and i am going to get some 3.73's soon..What all do i need to get for the 3.73's to get posi in it?? is it just the carrier to change or what?? Thanks Jason __________________ 7DOS - 1972 C-10 350/350 Porterbuilt/Accuair 20x8.5/20x10 Ride Low or Die PSSST - Yes it's bagged. 7dos build thread: http://67-72chevytrucks.com/vboard/s...d.php?t=610290

11-22-2002, 03:55 PM	#2
1971Stepside Almost Satisfied Join Date: Mar 2002 Location: Springfield, MO Posts: 2,932	Straight from my Randy's Ring and Pinion invoice: 1. YG GM12T-373 Ring and Pinion......149.99 2. AK 1559 Axle Bearing and Seal Kit......29.50 3. EAT19556 12T 3.73 HD Posi, Complete 30spl....340.00 4. YKGM12T 12 bolt GM Truck Install Kit. Includes shims, crush sleeve, carrier bearings, etc................83.36 5. SVOM19519546A Positraction Additive.........3.00 6. 2 Quarts of 80-90 weight gear oil.......8.00 (I bought this local) There you go. Dig into the penny bank and go for it. I got mine set up by a pro for $70.00. I think I have around 584.00 in the whole thing. The rearend was out of my truck and fully disassembled. __________________ 1971 C10 Stepside. LSx 6.0 with BTR Stage IV, Speed Engineering Headers, 4L80e transmission w/3200 Circle-D Stall. 3.73. Posi. Purchased this truck when I was 17. I started the rebuild (or take apart) in 1993. I have drug it around all over the country in pieces. Finally back on the road in 2021. "I can't complain, but sometimes I still do. Life's been good to me so far."

11-22-2002, 04:05 PM	#3
c10crazy Like a Rock! Join Date: May 2002 Location: USA Posts: 1,092	You mean $684, right?. How much difference did it make?. __________________ 69 LWB Runs great - work in progress Mess with me and you mess with the whole trailer park!

11-22-2002, 04:19 PM	#5
1971Stepside Almost Satisfied Join Date: Mar 2002 Location: Springfield, MO Posts: 2,932	No, the price I showed on the posi is what they advertise the thing for. I got it for considerably less (270), but I don't want to put them in a bind on that price and be "false advertising" for them. I found the posi for 280 at tom differential and they beat it. As far as performance it will be another year and a half before I know. I am doing a full frame up on the truck. __________________ 1971 C10 Stepside. LSx 6.0 with BTR Stage IV, Speed Engineering Headers, 4L80e transmission w/3200 Circle-D Stall. 3.73. Posi. Purchased this truck when I was 17. I started the rebuild (or take apart) in 1993. I have drug it around all over the country in pieces. Finally back on the road in 2021. "I can't complain, but sometimes I still do. Life's been good to me so far."

11-22-2002, 04:37 PM	#6
crazy longhorn Fabricate till you "puke" Join Date: Jun 2002 Location: Ill Posts: 9,402	Alexis, you can swap a posi unit in where ther was an open carrier. You just need to have the proper series carrier for the gear set that you chose. 3.73 is on a 4 series carrier....3.73,4.10,4.56 ect. The 3.07 is on a 3 series carrier(3.07-3.42), So to change from a 3.07 gear to a 3.73, you will also need a carrier change to a 4 series. ......the housings are all the same (12 bolt), with the exception of the tube widths on different yrs......crazy AL __________________ 69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears....

11-22-2002, 04:19 PM	#4
Alexis Member since 2000 Join Date: Dec 2000 Location: Mountain View Ca / Mexico Posts: 7,874	didn't someone post that if the 12-bolt didn't come with posi or somthing from the factory, that you couldn't swap in a posi cause of the size of the diff. inside.

11-22-2002, 05:07 PM	#7
Alexis Member since 2000 Join Date: Dec 2000 Location: Mountain View Ca / Mexico Posts: 7,874	thanks crazy longhorn...........always good to clear up info.



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