Rearend swap

[padresag]

Originally Posted by Captainfab

The 3 series carrier has the ring gear flange farther from center than a 4 series carrier.....kind of hard to describe. I don't happen to have one handy to measure. If I can find time tomorrow, I'll see if I can get a measurement and post here. The 3 series carrier will only work with 3.42 gears and higher. The 4 series carrier will only work with 3.73 gears and lower. There are no 3.54 gears for the 12 bolt, just 3.42's. The 3.54 gears are available for the Dana differentials.

the 3;54 are a dana. gmc used them
ron

[Jeff La]

Thanks Captainfab for the explanation

[Captainfab]

Here are a couple pics with measurements, of a GM truck 12 bolt 3 series carrier (3.42 gears and higher). It's hard to tell with the camera angle in the 3rd pic, but the measurement to the center of the center pin hole is 2". I didn't have a 4 series carrier out of a housing. I'll see if I have time to do that tomorrow. The 4 series carrier has the ring gear flange closer to the center pin.

[64shortbed]

Why did no one happen to say i will/ may need the mounts and u-bolt from the 85 to mount the rear end back under my truck? I got the old one out slide the new one under it and now i cant go any further because i can not use my old bolts and mounts. I hope when my friend calls me back he has some laying around.

Sorry just blowing off steam!
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