Looking to replace front and rear axles...

[ChrisCostlow]

I have a 72 Blazer CST. It sports a 350HO with only 1600 miles and Holley Terminator EFI. Tranny and NP205 have both been redone. New carpet, dash panel, seats, doors, and I just got a perfect rear hatch from a guy in my town.

Here's my problem. The PO put a one-ton axle in the rear and a three-quarter ton axle in the front. With that combination I can't get a 3.07 ratio. It's currently 3.83 (I'm told that's the lowest common ratio between the two axles) and works way too hard at 70 mph. I understand 3.07 was the stock ratio for my truck and that's what I want to go to. I'd also like to take away most of the lift but know nothing at all about suspension. I had someone tell me "the shackles have been flipped" but can't find pics anywhere of what the stock setup looks like so if anyone has pictures I'd love to see them!

I'm gonna bite the bullet and sell the Harley to get this done but I need some help and info. I'm in So. Cal. in the mountains and need to know what axles I need and where I can find them. I know I need half-ton axles but can I get them complete from wheel stud to wheel stud? Where to find them? I'm willing to as far as say, Phoenix.

Help me out Guys and Gals!

Thanks in Advance
Chris

[87Skier]

It's hard to say exactly what will need to be done without knowing the specifics of your lift. You are correct that the stock ratio for these trucks is 3.07 with 3.73, and 4.10 being options. These usually came with a Dana44 front and GM 12 bolt rear. Your best bet would probably to get a rolling chassis (I've seen several on craigslist) with the axle ratio you want. You probably won't get lucky and get a locker or posi unit, but at least you know that the front and rear are geared the same and many stock ones will have all the suspension parts you may need.

It's best to pull the covers and verify the gearing and condition before buying though.

[notsolo]

Too Bad your 3000 miles away, I have front and rear 72 axles with 373 gears left over from my conversion to 2wd. As 87 Skier said look for a donor, 71 and 72 trucks and blazers should be the same with disc brakes. Rear drive shaft on truck would be longer.

[cleszkie]

Thought I just saw a set of 1/2 axles (12 Bolt/Dana 44) out of a 72 Blazer in Orange County, CA craigslist not to long ago. These should be pretty easy to find. A set out of later model Chevys will also work with the 12bolt rear and 10 bolt front.

[hemi43]

Just my opinion, but why go through all that effort to change the diffs?? Why not upgrade to an overdrive transmission? That gear ratio you have right now is perfect.
I just got rid of the 3.08s in my truck and went to 4:10s. I have an OD transmission and 33" tires. The combination is absolutely perfect, tons of bottom end and cruises at 60 MPH at around 2000 RPM.

[ChrisCostlow]

Wonder how much it would cost to ship them.

Originally Posted by notsolo

Too Bad your 3000 miles away, I have front and rear 72 axles with 373 gears left over from my conversion to 2wd. As 87 Skier said look for a donor, 71 and 72 trucks and blazers should be the same with disc brakes. Rear drive shaft on truck would be longer.

[franken]

Chances are the U-joints are different, and DS length so more work there.
I wonder what the rear came out of. If they put a diff from a square in, then swapping back to a correct earlier diff could be not so easy.

What's funny is I want to swap the other way to the bigger diffs on my 72 K10.

[ChrisCostlow]

I searched the OC Craigslist for "blazer" and didn't see any axles. I'll keep lookin'. It would be so *****in' to find 'em right here at home LOL.

Originally Posted by cleszkie

Thought I just saw a set of 1/2 axles (12 Bolt/Dana 44) out of a 72 Blazer in Orange County, CA craigslist not to long ago. These should be pretty easy to find. A set out of later model Chevys will also work with the 12bolt rear and 10 bolt front.

[JNSM653]

If you are coming down the mountain this Friday or Sat come down the 38 into Mentone I've got a 69 K5 with unmolested hangers you can look at. I did however swap to 3/4 running gear 10yrs ago with 4.10's and 33's and am happy with it, running a ZZ4 with SMI Quadrajet and sm465 2600rpm at 65ish.
If you are going to swap axles find something close to that year at some point the axle/spring perch on the rear changed. My running gear is out of a 78 and I had to change rear perch location, not hard just letting you know.

[ChrisCostlow]

Originally Posted by JNSM653

If you are coming down the mountain this Friday or Sat come down the 38 into Mentone I've got a 69 K5 with unmolested hangers you can look at. I did however swap to 3/4 running gear 10yrs ago with 4.10's and 33's and am happy with it, running a ZZ4 with SMI Quadrajet and sm465 2600rpm at 65ish.
If you are going to swap axles find something close to that year at some point the axle/spring perch on the rear changed. My running gear is out of a 78 and I had to change rear perch location, not hard just letting you know.

Thank you so much. Can't come down this weekend as I manage the disposal company up here and I'm on duty. Some other time though if that's okay. I'll be posting pictures of mine in the next few days.

[JNSM653]

Anytime!!!

[Lieferson]

Some 72 blazer axles with 3.07 gears just went up on Craigslist in the Seattle area for 250$ not more than 4 hours ago

[ChrisCostlow]

The first picture is of what I believe to be the stock leaf spring setup on a '71 Blazer, and the second shows how MY '72 blazer is set up. I've never seen anything like what my Blazer has. My question is how hard is it to go back to the stock setup?
[IMG][/IMG]
[IMG][/IMG]

[SS Tim]

It all depends on what has been modified and how much you are willing to spend. It shouldn't be too much trouble though.
You are correct about the first picture being stock with tapered negative arch springs.