Question on Rear End Conversion - The 1947 - Present Chevrolet & GMC Truck Message Board Network

farmerj2000 · 01-16-2003, 03:17 PM

Hello,
I am new to this board and a new owner of my 1970.

I have a 1970 Chevy Step Side. I am in the process of restoring. The rear is stock and not posi. I would like to convert it to posi with 3.73 gears. I have someone doing most of the work and he told me I needed to order the following

12 Bolt Posi
3.73 Gear Ratio
+Setup Kit

I went to both www.summitracing.com and www.jegs.com

I am a little confused I on what exactly I need. Sorry but I am a newbie.

Anyone have any idea's? Any help would be greatly appreciated.

Thanks

70 longbed · 01-16-2003, 03:32 PM

Farmerj2000,

I am in the process of putting a posi into my 70, also. If you go to the bottom of the page and do a search on posi, I am sure that you will find more than enough information to confuse you.

I found a used setup from someone here on the board, but you can buy new stuff. There are several suppliers listed on the home page that can help you, or yu can go to a myriad of places on the web.

Basically you need a positraction carrier unit, a ring and pinion gear, and the installation kit (bearings and seals and such) to do the work. There are some alingments to worry about, so your plan to have the work done is probably a wise choice.

This is a great place for information and support. Hang in there, read some of the posts, and good luck.

**1971Stepside** · 01-16-2003, 03:40 PM

go to www.ring-pinion.com I bought all of my stuff for my 3.73 posi from Randy's. Great people to work with and they will answer all of your questions on the phone. Cheapest around as well.

I bought the following (going from memory here)

3.73 Ring and Pinion
Eaton 3.73 Posi Unit
Set up Kit - includes pinion bearings, seals, crush sleeve, etc.
Axle Bearing Kit (for bearings on outer ends of tube)
Posi gear oil
2 quarts of 80-90W gear oil (non synthetic)
chrome pumkin cover

Hope this helps and welcome to the board!!

70c10 · 01-16-2003, 04:06 PM

Welcome from Maryland. I went thru this last Saturday. I already had 3:73 gears in my truck. I bought an Eaton Posi , carrier bearings and races, and a new chrome cover plus fluid and additive. This cost me $371 with shipping the parts included. I paid a friend of a friend $100 to install it. Took him 2 hours. Hope this helps!

still w.i.p '68 · 01-16-2003, 04:26 PM

70C10, where did you get your posi unit?

70c10 · 01-16-2003, 04:34 PM

I bought it from www.tomsdifferentials.com in California for $280.

**Tim Christian** · 01-16-2003, 04:50 PM

Don't have no-Posi! But Welcome to the board!!!!!!!!!

01-16-2003, 03:17 PM	#1
farmerj2000 Registered User Join Date: Jan 2003 Location: Sterling, VA Posts: 7	Question on Rear End Conversion Hello, I am new to this board and a new owner of my 1970. I have a 1970 Chevy Step Side. I am in the process of restoring. The rear is stock and not posi. I would like to convert it to posi with 3.73 gears. I have someone doing most of the work and he told me I needed to order the following 12 Bolt Posi 3.73 Gear Ratio +Setup Kit I went to both www.summitracing.com and www.jegs.com I am a little confused I on what exactly I need. Sorry but I am a newbie. Anyone have any idea's? Any help would be greatly appreciated. Thanks

01-16-2003, 03:40 PM	#3
1971Stepside Almost Satisfied Join Date: Mar 2002 Location: Springfield, MO Posts: 2,932	go to www.ring-pinion.com I bought all of my stuff for my 3.73 posi from Randy's. Great people to work with and they will answer all of your questions on the phone. Cheapest around as well. I bought the following (going from memory here) 3.73 Ring and Pinion Eaton 3.73 Posi Unit Set up Kit - includes pinion bearings, seals, crush sleeve, etc. Axle Bearing Kit (for bearings on outer ends of tube) Posi gear oil 2 quarts of 80-90W gear oil (non synthetic) chrome pumkin cover Hope this helps and welcome to the board!! __________________ 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."

01-16-2003, 04:06 PM	#4
70c10 67-72 Addict! Join Date: Feb 2002 Location: The TAX State! Posts: 7,856	Welcome from Maryland. I went thru this last Saturday. I already had 3:73 gears in my truck. I bought an Eaton Posi , carrier bearings and races, and a new chrome cover plus fluid and additive. This cost me $371 with shipping the parts included. I paid a friend of a friend $100 to install it. Took him 2 hours. Hope this helps! __________________ Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads

01-16-2003, 04:26 PM	#5
still w.i.p '68 Dreams are free Join Date: Dec 2002 Location: Hogansville Texas Posts: 546	70C10, where did you get your posi unit? __________________ '68 swb fleetside originally w.i.p '68 member since 1-01 w.i.p = ( work in progress )

01-16-2003, 04:34 PM	#6
70c10 67-72 Addict! Join Date: Feb 2002 Location: The TAX State! Posts: 7,856	I bought it from www.tomsdifferentials.com in California for $280. __________________ Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads

01-16-2003, 03:32 PM	#2
70 longbed Senior Member Join Date: Oct 2002 Location: Sierra Vista, AZ Posts: 489	Farmerj2000, I am in the process of putting a posi into my 70, also. If you go to the bottom of the page and do a search on posi, I am sure that you will find more than enough information to confuse you. I found a used setup from someone here on the board, but you can buy new stuff. There are several suppliers listed on the home page that can help you, or yu can go to a myriad of places on the web. Basically you need a positraction carrier unit, a ring and pinion gear, and the installation kit (bearings and seals and such) to do the work. There are some alingments to worry about, so your plan to have the work done is probably a wise choice. This is a great place for information and support. Hang in there, read some of the posts, and good luck.

01-16-2003, 04:50 PM	#7
Tim Christian Senior Member Join Date: Dec 1999 Location: TN/VA Posts: 6,388	Don't have no-Posi! But Welcome to the board!!!!!!!!!

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