The Stovebolt Site Forums The Shop Area Engine Shop dana 60 vs gm 14 bolt full floater

okay,
I have a 66 3/4 ton with an eaton h052 4:56 ring/pinion. originally i was all set up to swap in a 1/2 ton rear end with a 3:07 ring/pinion. truck was up on stands, tools ready, etc. came to find out ring gear was missing some teeth. lost a $100 bucks and learned a valuable lesson. trusted a complete stranger.
that's okay, really wanted to keep my 8 lug an 8 lug and did not want to change out my entire front end to make it a 6 lug. so....after almost a years research it comes down to a dana 60 or gm 14 bolt for a "higher" ring and pinion. if i go with the 14 bolt i can get a 3:42 ring/pinion. the dana i can get a 3:54 ring/pinion.
first question, would i notice a difference between those two gear set ups? they seem very close to me.
also, my eaton measured 65" aproximately from wms to wms. every 14 bolt i have measured comes in at about 67" wms to wms. the dana comes in at 65" which matches the original eaton. i am and will always run skinny steel wheels so width doesn't bother me, other than I want the front and back to have the same width. originally i thought i would go with the 14 bolt, but after seeing the dana i like the vintage correct look, the exact right width.
wondering what you fellas think. hope i am making the right decision. i realize the 14 bolt is a little friendlier with parts, but i am leaning towards the dana. toughness doesn't matter to me, as this will be a cruiser and mostly just carry my surfboard!
share your thoughts, and thanks in advance for any comments or suggestions.
Doug

Eiher one would do, the 14 bolt is stronger and is more comparable in stength to the Eaton, but the 60 is plenty strong for what you're wanting to do. As far as parts go, they're about the same. You'll find the 60 under just about any 3/4 or 1 ton service van, regardless of vehicle make.

thanks Bill,
what do you think about 3:42 versus 3:54 ring/pinion?
splitting hairs?

Without a lot more detail on your engine, transmission and tire choices in addition to how you plan to load and use the truck, this would be a hard call to make.

I chose to put a 14-bolt with 3.42 gears under my 1-ton project and those gears where part of the decision, but just because its right for me doesn't make it right for you.

Are you sure you're dealing with a Dana 60? I don't think the Dana looks that much different than the GM axle so that consideration doesn't make sense to me.

However I have two Dana 70HD axles that are under or from GM trucks, so I would not hesitate to use a Dana under your truck.

I guess what I mean by the "vintage look" is really just the diff cover. I am so used to the 14 bolt cover on the newer stuff that I guess it looks a bit unique to me under something like a 66. The 10 bolt cover on the Dana just looks more vintage and simpler to me.
The motor is a mild re-furbished 350 with a quadrajet and dual exhaust. Tranny is a 4 speed on the floor with granny gear low. I believe it is what they call the sm420? Not sure on that one though.
Tires are 235/85/16.
I want to drive this truck to work and back as a daily driver. Work is 16 miles one way, all freeway. That is why I originally intended on going with the half ton 3:07. Really just want to cruise in this truck, not hotrod.
Thanks again Bill

I'd go with the D60. It matches your width more closely and I don't think the difference between 3.42 and 3.54 won't be enough to notice that much. Maybe a couple mph difference at a given rpm at highway speed.

thanks steve,
that's the way i am leaning also

I agree, mathing the widths would be best but the GM is sure a lot easier to work on.

My '67, 3/4, steel bed, GMC came from the factory with a 4.56 Dana rear. I found 3.54 gears and posi carrier in a Dodge 3/4 auto, 440 and put them in my axle. Everything is the same except I had to find a different yoke because Dodge uses smaller U joints.
As longbox said, the parts are readily available and mostly interchangable.
As wrenchbender said, the GM 14 is a lot easier to set up.
Changing the 4.56 gears for 3.54 gears was the best thing I have done to this truck. The difference is night and day.
I have a SM456 4 spd, similar to your SM420 and a 292 six.
The second best thing I have done to it is the AC. P-steer and disc brakes rank 3rd and 4th.

Last Sunday I ran out across the desert to El Mirage at 70-75 mph with two bikes in the back to watch the land speed cars run.
With those gears and the other changes a trip like that is just as easy as with a newer truck.

thank you guys for the info.
yeah, i officially went with the dana 60 today with the 3.54 ring/pinion.
i can't wait to try this truck on the freeway after the install.
Richard, i have always wanted to make that trip out to el mirage!
i am fortunate to live in a place where we really don't need ac. we don't have it in our house, and i really will never need it in my truck. the drum brakes with single master cylinder stop the thing on a dime, but when you have 4.56 ring/pinion you barely need to use the brakes!
the power steering on the other hand, that will be my next upgrade. turning this thing in tight beach parking, on small streets, can be a bit challenging.
thank you all for the communication, i will let you know how it turns out after this weekend.

Got my truck back a few days ago with my new differential. It now boasts a Dana 60 with a 3:54 ring and pinion. WHAT A DIFFERENCE! I now cruise on the freeway at 70 mph! Its kind of weird, because 2nd and 3rd feel just a bit difference, but when I shift into 4th it drops WAY down. Taking some getting use to.
Now, it is time to get to my fuel sending unit. Ran out of gas for the 2nd time and got stranded on the side of the road! Crappers.
Anyways, love my new gears...

You're probably still shifting as much by vehicle speed as engine speed, so when you make that 3rd to 4th shift at about the same mph as before you're feeling the full rpm benefit of the change.

I could not say in daily driving that it really matters, but I'd expect your ideal shift points are now somewhat faster (mph) than they were before.