Axle swap

[JLubben]

I didn't have much success in finding the info. Might not have searched correctly.

I have a 72 K20. Are there any simple axle swaps to say a newer 14 bolt and such? Are the spring perches the same? What would be good for the front then if I wanted to upgrade from teh D44 there?

Also, I have the 8x6.5 lug pattern, when did they stop that pattern? I want to be able to keep my rims and tires as well.


The reason, is I want to go to a little taller gearing. the 4.10:1 in mine is a bit low for what I do for driving. And getting stuff for the eaton in the rear may be rather spendy as well.

Thanks!

[Caddylackn]

If you have the Dana 60, believe it or not, that is still considered a modern axle. Dodge used the Dana 60 until 2004, Chevy until 2012, and Ford until 2012. I think the GM corporate 14 bolt was phased out in '86.

The spring perches and locations of Dana 60s will vary between makers, but those can be swapped around moved, and rewelded. They make a ton of aftermarket heavy duty parts for a Dana 60 including rear disk brakes, lockers, air lockers, spools, etc. The only problem is you can't get a gear ratio numerically lower than 3.54 on a Dana 60.

The 8 x 6.5" pattern is also common to old and modern style wheels until 1999 for ford and I think 2004 Dodge and 2012 Chevy. Stay away from the ford metric 8 lugs after 1999, they won't fit. Some old chevy wheels may not fit on a Ford Dana 60, since Ford used larger drums and there may be clearance problems with old chevy 8 lug wheels.

[Mike C]

The one ton 14 bolt is a bolt in with 40.5" spring centers. The 3/4 ton is not on 42.5" spring centers so perches need to be moved. Shock mounts need relocating on both. The old style 14 existed until end of the V30 trucks in '91 maybe longer in 3/4 ton vans but they are a different width.

The K30 Dana 60 is a bolt in. Available from 77-87 in the 4 wheel drive one tons and the V30 again until '91.

Does your truck have a Dana 60 or an Eaton rear? You have discs on front any reason you feel you need/want to move to the K30 stuff?

[TwoFiftyShifter]

Originally Posted by Mike C

The one ton 14 bolt is a bolt in with 40.5" spring centers. The 3/4 ton is not on 42.5" spring centers so perches need to be moved. Shock mounts need relocating on both. The old style 14 existed until end of the V30 trucks in '91 maybe longer in 3/4 ton vans but they are a different width.

The K30 Dana 60 is a bolt in. Available from 77-87 in the 4 wheel drive one tons and the V30 again until '91.

Does your truck have a Dana 60 or an Eaton rear? You have discs on front any reason you feel you need/want to move to the K30 stuff?

He stated his reasoning. 4.10 gears on an Eatom

[Mike C]

Thanks. I missed that.

3.73 are fairly common in the 14 bolt, but 60's are more uncommon in that ratio as it seems most are from CUCV trucks with 4.57.

Personally, I would just run taller tires!

[jeffahart]

What size tires are you running? Maybe just up the tire size. I like the 4.10 gears myself. But ya, like everyone said the 1 tons are a bolt in on the rear, but you may have to re-weld in new the shock mounts, but you can drive it without shocks and have them welded in after the install, no biggie. But back to tires, even if you can borrow some larger diameter tires from a friend, and only put on the rear and see if it gets the RPM where you want. Just don't engage the front with only larger tires on rear. That way maybe you can see if just buying new tires will get you at comfortable RPM range.

I moved off the eaton for a 14bolt also, but I got off a CUCV so I now have 4.56 the opposite direction you want.

Here http://67-72chevytrucks.com/vboard/s...d.php?t=641965

[JLubben]

I have 33" tires and a 4" lift. Don't want bigger tires than what I have now. The 14bolt corporate is a direct bolt in? Minus the shock mounts? I thought the perch center to center was different?

I was hoping for 3.73 or even 3.42 maybe, but not sure what front would work as well. The D44 seems rather light duty for a 3/4t truck.

[Mike C]

As said above, the 1 ton is a direct bolt in as it has 40.5" spring centers. The 3/4 ton is not as it has 42.5" spring centers.

Both need shock mounts relocated.

[JLubben]

Ahh Ok, I read that as the 3/4 tons were different than the 1 tons. I have a 3/4 ton is why I thought the perches were different. So the 72's have the 40.5" then? I'm not near the truck right now to measure is why I ask.

Still curious what would fit in the front then? I'm not worried about the durability on the front. I just want to make sure I have parts available and such.

I may eventually want discs on the rear. Not sure if a newer one with discs will bolt up the rear of my k20?

Hydroboost is going to eventually replace my vacuum booster in the future.

This here is my baby!

[Mike C]

Any 73-91 8 lug solid front GM will bolt up. K20, Suburban, K30 (Dana 60=expensive) either 10 bolt or Dana 44.

The '67-'72 trucks are 40.5" spring center in 4x4 and they are 42.5" in 2x4.

On my Jimmy I swapped from an '86 Suburban the semi-float 14 bolt with 4.10 in the back and bolted the 8 lug disc parts onto my original Dana 44 that I had put 4.09 gears in years ago instead of using the complete 10 bolt which would of been easier!

I built a jig off the 12 bolt housing to align the perches and shock mounts. I used the GM perches that I cut off the SF 14 and I used a set of shock mounts I cut off one of the 5 12 bolts I had broken over the years...

Shock mounts for the 12 bolt tucked nicely above the bottom of axle tube so nothing to get hung up offroad.