CK5
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Best rear axle swap
- Thread starter ajak5
- Start date
What's the intended use? Any future plans for an 8 lug axle swap?
I drive it around town and take it off-road once in a while nothing crazy
I like the 6 lug 14 semi floating axle, I had one in my '90 for a while. But keep in mind that it isn't a bolt-in swap. The leaf spring pads need to be moved since they were originally under IFS trucks. And there are 2 different widths of them, the 2wd version is about the same width as your factory rear axle. Then there is a slightly wider one.
Another vote for a 14 bolt semi floater.
although you can get an 8 lug that is a bolt in, I happen to have one in 3.73
Im gonna say the best to swap in is the exact same thing you have now. If youre ready for an upgrade, the 6 lug 9.5 14 bolt is ideal and has very little collateral damage.
Yes, however that would require doing something with the front axle as well as wheels, possibly tires too. I don't remember what the specifics are for changing one of those to 6 lug, but I thought that it took some digging for parts and swapping more stuff around.
I was able to put 1/2" studs in the rear axles without modifications, then drilled the front hubs and rotors to go to 1/2" studs. Then I had upgraded wheel studs and kept my wheels and tires. Also I didn't have any great change in the conical seat area of the wheels that can happen with the metric studs and some wheels.
I say Dana-80 with disc brakes. 
There are several options out there and it just depends on how much time and money you want to spend on it, and whether some of the options are really worth it or not. The cheapest and easiest solution would be to find a matching axle in the junkyard and bolt it in. Downsides are that axle is going to be at least 30 years old for a direct bolt-in, so a little harder to find and you always take a chance on junkyard parts. Next option, and since you said a new housing is needed, is to find any gear ratio 10-bolt from that era truck and rebuild it. Downside to that is it's not exactly cheap especially if you have to pay a shop to do the work. If you did a new posi, gears, bearings, seals, etc... you are easily in the $1,000+ range after labor. The SF 14-bolt is a big upgrade in strength but as mentioned a mostly bolt-in version would only be 8-lug and still dealing with a 30 year old axle and would need to address the front. Swapping the front axle over to 8-lug is not that big of a deal if you can find the parts.....lots of 8-lug front 10-bolts were made but again it's been 30 years since they came out of the factory so junkyards parts are getting a little scarce. For wheels you could buy a fairly cheap set of 15" 8-lug steel wheels (assuming you are running 15" tires and want to keep them). Brings back memories....when I swapped my K5 over to a 14-bolt FF rear axle and went from 6-lug to 8 lugs in the front I think I paid $150 total for everything.....but that was 15-some years ago.
I have a six lug 9.5" 14 bolt with 3.73 gears just laying around. I got it for my cucv and then never used it.
I used a 91 suburban 8 lug housing (bolt in) I used 94 suburban 6 lug axles (aftermarket moly) and a 1/2" spacer.to move the brake backing plate out. Found a pristine set of 3:73 g80 in a 97 pickup. I've got maybe $400 in it, drove it to a real mechanic to have him check my work. He charged $200 to make it right. I don't mind rear drums. I am not a mechanic, I just work on stuff. Couldn't have done it without the talent on ck5.
Where did you find the spacers ? I have searched everywhere and can only locate them at Hillbilly Wizard. He wants a fortune for them ! It would be cheaper to have some fabricated at a local machine shop I think.
Local shop $40 took the backing plate for template, 1/2" steel plate.
Zombie thread
Copy, thanks for the reply
That’s because OP said “best rear axle swap”…
A ‘73~’81 12B would be an easy swap but not a true upgrade and certainly not in the best category.
A ‘73~’81 12B would be an easy swap but not a true upgrade and certainly not in the best category.
