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Discussion Starter #1
Im trying to figure out if my truck has a 7.5 rear end its a 94 gmc sierra 4.3 v6 im going to start swaping an ls1 and wanted to swap the rear end to a 8.5 and add some gears to it ( if mines a 7.5
 

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High Performance Rear Ends
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S series truck or full size 1/2 ton? If it's a full size 1/2 ton then it's the 8.5 rear end. The 7.5 was not used in full size trucks.
 

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Sierra is a full size. The Sonoma was the S10 variant.. so it has an 8.5" unless it's got the F44 package and then it would actually be a 9.5" 14 bolt
 

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Sierra is a full size. The Sonoma was the S10 variant.. so it has an 8.5" unless it's got the F44 package and then it would actually be a 9.5" 14 bolt
Yes sir, Sierra does signify full size GMT-400 truck. RPO F44 signifies the "heavy half" that gets the 14 bolt 9.5" Semi Floating rear end.
If this is a 2wd Sierra, F44 will trigger the upgrade to 6 lug wheels, same as teh 4wd. The only 14 bolt 9.5" SF with 5 lug wheels was the 1990-1993 454SS, axles of which, are impossible to find.

Does F44 automatically get rpo Mt1 4l80-E? I'm guessing yes?

thanks

peace
Hog
 

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High Performance Rear Ends
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What gears are in it now? What do you want to do with it? What transmission will you be using? How tall will the rear tires be?
 

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Discussion Starter #9
It has stock gears I was thinking 3.73 gears im putting an ls1 that comes with a 4l60e im trying to keep the engine stock at first but later im going to add heads and mild cam
 

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Proud LOSER
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3.42 to 3.73 is not worth the effort..... likely a big tire on it and an OD, at least 4.11's would be a good start. May even want a 4.56 depending on tire size.
 

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I wanted 4.10s but one of my friends mentioned the fact that It was my daily driver
What size tire on it? Stock 5.3 4L60 GM trucks come with 4.10's as an option. My avalanche had 33" tires and 3.73's and it sucked, was lazy out of the hole. Was awesome on the highway if you didn't mind cruising at 80mph.
 
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