The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1967 - 1972 Chevrolet & GMC Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 04-20-2019, 06:23 PM   #1
jcwren
Registered User
 
Join Date: Nov 2018
Location: Flowery Branch, GA
Posts: 206
TDA-stamped rear end to posi conversion?

I've got a 6-lug 3.73 open rear end in my '70 that I'd like to convert to posi. It's stamped with 'TDA 1001 W', which tells me it's 3.73 open, manufactured in Warren, MI on 10/01.

If I've decoded things right, this should be a 8.5", 12 bolt, 30 spline, type 3 housing rear end?

Can I just swap the open guts with posi guts, like an AuburnGear unit or thisYukon Dura Grip, and I shouldn't need to do anything to the housing or axle tubes, correct?
Attached Images
 
__________________
1970 C10 LWB Stepside
1971 Dodge Dart
1993 Buick Roadmaster Estate Wagon

Last edited by jcwren; 04-20-2019 at 06:31 PM.
jcwren is offline   Reply With Quote
Old 04-21-2019, 11:40 AM   #2
flashed
Registered User
 
Join Date: Oct 2009
Location: canton ga
Posts: 12,729
Re: TDA-stamped rear end to posi conversion?

Im in for your answer as I plan the same thing .
flashed is offline   Reply With Quote
Old 04-21-2019, 11:44 AM   #3
Two-Piece
Registered User
 
Join Date: Mar 2015
Location: Taylor, TX
Posts: 34
Re: TDA-stamped rear end to posi conversion?

That is exactly what I did. Have the same 12 bolt with 3:73's. Dropped in a posi until and it works great.
Two-Piece is offline   Reply With Quote
Old 04-21-2019, 12:36 PM   #4
flashed
Registered User
 
Join Date: Oct 2009
Location: canton ga
Posts: 12,729
Re: TDA-stamped rear end to posi conversion?

What Posi unit is the best or are they both equal in price and quality ? jcwren ,not trying to Hijack your thread , just got my 5 lug rear end and doing the same upgrade .
flashed is offline   Reply With Quote
Old 04-22-2019, 05:09 AM   #5
'68OrangeSunshine
Senior Member
 
'68OrangeSunshine's Avatar
 
Join Date: Feb 2002
Location: Tucson, AZ USA
Posts: 6,980
Re: TDA-stamped rear end to posi conversion?

While my first choice would be an Eaton Posi, because they're rebuildable, OEM, and bombproof -- I put an Auburn posi in the 12-Bolt Corp 3.73 rearend on my '67 K/10 Suburban. let it sit for 10 years after the sub's engine fire. changed out the rear brake sets for 11-1/2'' [drums w/ finns] and 2-1/2'' brake shoes to match my '71 K/1500 Jimmy.
When that truck's factory 12-Bolt w/ factory Eaton posi blew out. I cannibalized the Sub's whole rear assembly for the Jimmy. Nine years later still rockin'n' rollin' on that Auburn posi.
[Now if I only had the bread to bring back the Suburban....?]
__________________


Every 25 years I like to rebuild that 292, whether it needs it or not.
'68OrangeSunshine is offline   Reply With Quote
Old 04-22-2019, 12:25 PM   #6
jcwren
Registered User
 
Join Date: Nov 2018
Location: Flowery Branch, GA
Posts: 206
Re: TDA-stamped rear end to posi conversion?

Thanks for the confirmation Time to go shop for a posi.

I thought I had a line on one a guy bought that wasn't correct for his truck, but it turns out his is a 28 spline for '73 and up. Woulda saved $150 if had been the part I needed...
__________________
1970 C10 LWB Stepside
1971 Dodge Dart
1993 Buick Roadmaster Estate Wagon
jcwren is offline   Reply With Quote
Old 04-23-2019, 07:55 AM   #7
Mike C
Registered User
 
Mike C's Avatar
 
Join Date: Dec 1999
Location: Austin, TX, USA
Posts: 7,709
Re: TDA-stamped rear end to posi conversion?

Quote:
Originally Posted by jcwren View Post
Thanks for the confirmation Time to go shop for a posi.

I thought I had a line on one a guy bought that wasn't correct for his truck, but it turns out his is a 28 spline for '73 and up. Woulda saved $150 if had been the part I needed...
If it was a 28 spline it would have been for an 8.5” 10 bolt as the truck 12 bolts were always 30 spline. And the 10 bolt didn’t show up until 1981 or so in the back of the 1/2 ton trucks. And they went to 30 spline in ‘88. But not interchangeable with a 12 bolt at any point.

Consider a Detroit TruTrac as well as the clutch type LSD.
__________________
44 Willys MB
52 M38A1
64 Corvette Coupe
68 Camaro 'vert LT1 & TH700
69 Z/28 355 12.6's @110
69 Chevy Short Step 4 1/2"/7" drop
72 Jimmy 4WD 4spd 4" & 35's
02 GMC 2500HD 4x4 Duramax
Mike C is offline   Reply With Quote
Old 04-23-2019, 10:37 AM   #8
GASoline71
"I ain't nobody, dork."
 
GASoline71's Avatar
 
Join Date: Sep 2007
Location: Whidbey Island, Washington
Posts: 8,921
Re: TDA-stamped rear end to posi conversion?

Main thing to remember about 12 bolts is the carrier spilt on truck 12 bolts is different than car 12 bolts. To run stock 3.73's in a truck 12 bolt you will need a 4 series carrier, where as the car 12 bolts went to a 4 series carrier at 4.11's.

You can use a 3 series carrier in a truck 12 bolt but will need a ring gear set with a thicker ring gear, or use a ring gear spacer.

I am not 100% sure that truck and car carriers are the same animal.

Gary
__________________
'cuz chicks dig scars...

My 1972 GMC 1500 Super Custom (Creeping Death) "long term" build thread.

The Rebuild of Creeping Death after the wreck

Quote:
Originally Posted by LONGHAIR View Post
I would never rebuild a 305.
Quote:
Originally Posted by prostreetC-10 View Post
I love using vacuum gauges as part of the carb tuning process. I hook the gauge to the inside of my garbage can and leave it there.
Quote:
Originally Posted by Marv D View Post
Remember Murphys 2nd law of mechanical relationships... "OPPOSING COMPONENTS ATTEMPTING TO OCCUPY THE SAME SPACE, AT THE SAME TIME, GENERALLY END UP OCCUPYING ADJOINING SPACE AT THE BOTTOM OF THE OIL PAN"
Quote:
Originally Posted by cableguy0 View Post
Its cheaper to listen to advice given when you ask for help than it is to ignore everyone and wait for carnage.
GASoline71 is offline   Reply With Quote
Old 04-24-2019, 08:13 AM   #9
Mike C
Registered User
 
Mike C's Avatar
 
Join Date: Dec 1999
Location: Austin, TX, USA
Posts: 7,709
Re: TDA-stamped rear end to posi conversion?

Car and truck differential cases are not interchangeable.
__________________
44 Willys MB
52 M38A1
64 Corvette Coupe
68 Camaro 'vert LT1 & TH700
69 Z/28 355 12.6's @110
69 Chevy Short Step 4 1/2"/7" drop
72 Jimmy 4WD 4spd 4" & 35's
02 GMC 2500HD 4x4 Duramax
Mike C is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 12:35 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com