Rear Diff Carrier - Series 3 or Series 4 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

dag19 · 08-23-2020, 10:34 PM

I have a leaf spring 12 bolt truck rearend that I would like to put 3:73's in. I am changing out the axles to a 30 spline 5 on 5 pattern. The pickup has a Gen III 6.0 LS with a 4l80e transmission.

What series of carrier would be best for the 3:73's? A 3 series or a 4 series? I ask because when I was perusing Summit and Richmond Gears, I see they offer 3:73's in both series. Also I intend to go with a Detroit TrueTrac.

roboticjunky · 08-24-2020, 12:33 AM

You'll need to go with the Series 4 because the TrueTrac only comes in Series 4 for a 12 bolt rearend for trucks. I just bought those same parts for my 72 chevy.

**HO455** · 08-24-2020, 02:04 PM

I believe that the 3.73 gear set for the 3 series carrier is the thick gear set. The three series carrier normally only goes as far 3.42.
Nothing wrong with thick gear sets (I'm running a set) just for very high performance applications there are drawbacks.

dag19 · 08-24-2020, 09:54 PM

Quote:

Originally Posted by roboticjunky

You'll need to go with the Series 4 because the TrueTrac only comes in Series 4 for a 12 bolt rearend for trucks. I just bought those same parts for my 72 chevy.

Well that settles that! Thanks Robot. I will go that same route with my pickup.

08-23-2020, 10:34 PM	#1
dag19 Registered User Join Date: Apr 2010 Location: Austin TX Posts: 135	Rear Diff Carrier - Series 3 or Series 4 I have a leaf spring 12 bolt truck rearend that I would like to put 3:73's in. I am changing out the axles to a 30 spline 5 on 5 pattern. The pickup has a Gen III 6.0 LS with a 4l80e transmission. What series of carrier would be best for the 3:73's? A 3 series or a 4 series? I ask because when I was perusing Summit and Richmond Gears, I see they offer 3:73's in both series. Also I intend to go with a Detroit TrueTrac. Last edited by dag19; 08-23-2020 at 10:42 PM.

08-24-2020, 12:33 AM	#2
roboticjunky Registered User Join Date: Oct 2015 Location: IN Posts: 209	Re: Rear Diff Carrier - Series 3 or Series 4 You'll need to go with the Series 4 because the TrueTrac only comes in Series 4 for a 12 bolt rearend for trucks. I just bought those same parts for my 72 chevy.

08-24-2020, 02:04 PM	#3
HO455 Post Whore Join Date: Feb 2016 Location: Portland Oregon Posts: 11,023	Re: Rear Diff Carrier - Series 3 or Series 4 I believe that the 3.73 gear set for the 3 series carrier is the thick gear set. The three series carrier normally only goes as far 3.42. Nothing wrong with thick gear sets (I'm running a set) just for very high performance applications there are drawbacks. __________________ Thanks to Bob and Jeanie and everyone else at Superior Performance for all their great help. RIP Bob Parks. 1967 Burban (the WMB),1988 S10 Blazer (the Stink10 II),1969 GTO (the Goat), 1970 Javelin, 1952 F2 Ford OHC six 4X4, 29 Model A, 72 Firebird (the DBP Bird). 85 Alfa Romeo If it breaks I didn't want it in the first place The WMB repair thread http://67-72chevytrucks.com/vboard/s...d.php?t=698377



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