TDA-stamped rear end to posi conversion?

[jcwren]

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?

[flashed]

Im in for your answer as I plan the same thing .

[Two-Piece]

That is exactly what I did. Have the same 12 bolt with 3:73's. Dropped in a posi until and it works great.

[flashed]

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 .

['68OrangeSunshine]

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....?]

[jcwren]

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...

[Mike C]

Originally Posted by jcwren

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.

[GASoline71]

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

[Mike C]

Car and truck differential cases are not interchangeable.