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07-04-2024, 07:36 PM
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#1 |
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Registered User
Join Date: Oct 2003
Location: San Jose Ca.
Posts: 3,334
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Upgrading to POSI
My 68 C10 will eventually have a 700r4 installed and the 3.07 open will be replaced with a 3.42 or 3.73 POSI. Have not made up my mind on the ratio yet.
What units are you guys using for your POSI? I have been told the GM80 is good and bad and there are others as well. Would like to get your opinions. Thanks!
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RIP to my son Dylan. 5/17/2002 - 8/18/2018 If you want to know more about rare forms of pediatric cancer or if you want to help fund pediatric cancer research, please check out the website for the non-profit I started. https://slothforpedcancer.org 68 build thread http://67-72chevytrucks.com/vboard/s...d.php?t=223234 |
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07-04-2024, 08:43 PM
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#2 |
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Senior Member
 
Join Date: Feb 2002
Location: Tucson, AZ USA
Posts: 7,172
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Re: Upgrading to POSI
Eaton is the stock unit, and they are stout and rebuildable. I've had good luck with Auburn. I prefer 3.73 in a halfton truck.
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Every 25 years I like to rebuild that 292, whether it needs it or not. |
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07-04-2024, 08:43 PM
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#3 |
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Registered User
Join Date: Jun 2015
Location: Carlos MN
Posts: 2,001
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Re: Upgrading to POSI
I like and use Detroit Tru Trac. No posi friction lube needed.
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07-04-2024, 08:45 PM
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#4 | |
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Senior Member
Join Date: Jan 2015
Location: central oregon
Posts: 200
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Re: Upgrading to POSI
Quote:
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07-04-2024, 11:50 PM
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#5 |
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Senior Member
Join Date: Jan 2001
Location: Orem, Utah
Posts: 7,870
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Re: Upgrading to POSI
I also have a Tru Trac. I love it.
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I have sworn upon the altar of God, eternal hostility against every form of tyranny over the mind of man. - Thomas Jefferson |
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07-05-2024, 08:38 AM
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#6 |
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Senior Member
Join Date: Nov 2013
Location: East Tennessee
Posts: 2,128
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Re: Upgrading to POSI
For street use you, can't beat the Eaton TrueTrac,
I have them in all 3 of my trucks
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1967 C10 Step side 1968 C10 Step side 1970 Chevrolet K/5 Blazer 1972 Chevrolet K/5 Blazer ............. 
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07-05-2024, 10:09 AM
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#7 |
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Senior Member
Join Date: Dec 2014
Location: Edmonton Alberta
Posts: 1,321
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Re: Upgrading to POSI
I have a 700r4 with an Auburn 3.73, haven't put a lot of miles on it but its fun.
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DAVE Edmonton, Alberta 1959 Apache 1967 K20 1968 C20 1970 C10 1972 GMC 2500 1981 C10 |
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07-05-2024, 12:07 PM
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#8 |
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Registered User
Join Date: Oct 2003
Location: San Jose Ca.
Posts: 3,334
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Re: Upgrading to POSI
I will look into the Eaton TrueTrac. I plan on driving and using this truck maybe even a roadtrip or two
 Thanks!
__________________
RIP to my son Dylan. 5/17/2002 - 8/18/2018 If you want to know more about rare forms of pediatric cancer or if you want to help fund pediatric cancer research, please check out the website for the non-profit I started. https://slothforpedcancer.org 68 build thread http://67-72chevytrucks.com/vboard/s...d.php?t=223234 |
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07-05-2024, 12:51 PM
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#9 |
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Registered User
Join Date: Feb 2024
Location: Pleasanton CA
Posts: 140
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Re: Upgrading to POSI
Did the i6 equipped trucks have 3.73 from the factory in the 12bolt?
__________________
1969 C10 Shortbed Wanted (pm me): - Pair of 275/60/15 tires |
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07-05-2024, 01:14 PM
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#10 | |
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Registered User
Join Date: Aug 2020
Location: Salmon Arm BC
Posts: 159
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Re: Upgrading to POSI
Quote:
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1970 C10 l/b 292/4spd Build: http://67-72chevytrucks.com/vboard/s...d.php?t=811062 |
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07-05-2024, 02:32 PM
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#11 |
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Registered User
Join Date: Apr 2022
Location: Moorpark, CA
Posts: 738
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Re: Upgrading to POSI
the standard gear seems to be 3:73 in the I6 1/2 tons.
Get Eaton vs Auburn LS diff. Or the Eaton TruTrack. My $.02 is I prefer the LS vs TruTrack. 700R4 has a VERY low 1st gear so I would go 3:42's to keep the Fwy RPM's down. |
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07-05-2024, 03:04 PM
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#12 |
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Registered User
Join Date: Oct 2016
Location: Dallas Texas
Posts: 3,026
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Re: Upgrading to POSI
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700r4 here with 3.73 Eaton posi. The low 1st gear helps it get off the line quick and the rear gear keeps the RPMs in check at speed. 2000 RPM = ~75MPH, 2150RPM = ~80MPH. Hth, -Kevin
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67 C10 fleet fuel injected '70 402, 700r4, 3.73 posi 07 335 sport turbo 6sp 94 Trans Am GT LT1 6sp posi -- sold after 22yrs 99 540 sport V8 6sp -- sold 73 240z L24 4sp -- given to friend 68 C10 step 350/350 3.73 open -- sold |
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07-05-2024, 05:56 PM
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#13 | |
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Registered User
Join Date: Oct 2003
Location: San Jose Ca.
Posts: 3,334
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Re: Upgrading to POSI
Quote:
__________________
RIP to my son Dylan. 5/17/2002 - 8/18/2018 If you want to know more about rare forms of pediatric cancer or if you want to help fund pediatric cancer research, please check out the website for the non-profit I started. https://slothforpedcancer.org 68 build thread http://67-72chevytrucks.com/vboard/s...d.php?t=223234 |
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07-05-2024, 09:18 PM
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#14 | |
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Senior Member
Join Date: Feb 2002
Location: Tucson, AZ USA
Posts: 7,172
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Re: Upgrading to POSI
Quote:
__________________
Every 25 years I like to rebuild that 292, whether it needs it or not. |
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07-05-2024, 10:35 PM
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#15 |
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Registered User
Join Date: Feb 2024
Location: Pleasanton CA
Posts: 140
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Re: Upgrading to POSI
I’ll verify next time I have the truck in the air but if it already had 3.73s that would be awesome and one less thing to worry about.
Can anyone elaborate on the Eaton LS vs Tru Track? What is the cost difference? I want to be sure that when I pop that clutch both tires go up in smoke for many years to come on the street.
__________________
1969 C10 Shortbed Wanted (pm me): - Pair of 275/60/15 tires |
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