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Swapping a 10 bolt rear for a 14 bolt semi floater

Big T

Well-Known Member
Messages
3,748
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Location
Fullerton, CA
Ok, I got the rear end painted and bolted into the truck. All that is left is to get the drive shaft hooked up. I called the local Napa and they say they have the right conversion u joint in stock. I'll pick that up tomorrow and hopefully have that and the breaks hooked up.

Turns out, this 14 bolt sf is wider then the stock 10 bolt. I can't remember exactly how much now but I think it's a 3" difference. By the looks of it , the front and rear are about the same width now.

Another thing I noticed is the leaf spring perches on the 14 bolt rear are slightly shorter then the 10 bolt leaf perches. Not a big deal cause the back end was much higher before and the height difference is not really noticeable. Maybe has something to do with the increased axle tube diameter on the 14 bolt.
Was this 14 Bolt FF from a GMT 800? Those were approximately 3" wider. Also, the spring perches and the bounce pads were in slightly different locations. The mount for the brakes, at least the disc brake version, is a different pattern. We had to cut an weld new ones in place on ours from a GMT 800 to make it work with the GMT 400. Haven't done the install yet; that's a winter project. This conversion will get us disc brakes in the rear.

Curious, how much did you pay for the 14 bolt FF axle?
 

RoryH19

New Member
Messages
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6
Location
Texas
I've been looking to upgrade the rear diff of a K5 Blazer and found this thread.
I would like to keep the 6 lug wheels I have and swap a 14 bolt axle to replace the factory 10 bolt.
From what I've read I should use a 88-99 4x4 k1500 or light duty 2500 to have the same width axle and 6 lug bolt pattern.
I should also take the u-bolts and brackets from the donor.
Then use the conversion u-joint to keep my existing driveshaft.
Anything else I need to know?

The option code for 3.73 is GT4 and 4.10 is GT5 in the glove box I believe.
Is there a way to tell if limited slip from the option list or will I have to turn the wheels?

Thanks.
 

RoryH19

New Member
Messages
4
Likes
6
Location
Texas
I found a 99 4x4 Suburban with codes GT4 and G80, 3.73 gears and limited slip.
I plan to take the u-bolt plates and u-bolts if I don't have to cut when I remove.
Is there anything else I need?
 

MrMarty51

Well-Known Member
Messages
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1,837
Location
Miles City, Montana
Good point. I plan to pickup this weekend.
I did not know if You were removing the differential Yourself or if the yard was, just wanted to be sure You is fully equipped.
I found a brand new looking 12 point Snap On end wrench in the intersection of the town I go to for church services. I advertised it on that areas facebook page and no one claimed it. I caught the snap on man and told Him I had it if anyone in that area was in need of replacing one they had lost. He was the one that mentioned it may have been used to remove a drive shaft and was accidently over looked.
I do not remember the sizes but I think a 3/8ths, a 7/16ths, a ten and a twelve mm might get the job done.
I like to use My battery impact driver whenever I can get it into position, sure speeds things up.
 
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