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.

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.

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.

Re: Rear Diff Carrier - Series 3 or Series 4
 

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