Need opinions...14 bolt or Dana 70 for my '72 K25 dually conversion?

[superchevy]

After reading as many posts as I could, it looks like I'm down to a choice of a Dana 70 dually rear out of an '81 1-ton Chevy for sale locally, or finding a 14 bolt dually rear. Any opinions? I have a couple of questions on widths...my stock Dana 60 rear measures 65" WMS and 53.5" backing plate to backing plate...the Dana 70 is 59" bp to bp (don't have a wms number on it yet).
You guys that have done the dually/stepside fender conversion...what width rear end did you use? I read somewhere where the 14 bolt drw was a bolt in swap...is this true?
Thanks for the help.
SC

[DieselEater]

Either differential in dually form will have the narrow spring perches. As for strength, the 14-bolt has a far superior pinion design. The 70 has a weak pinion......Neither should give you any problems though. 14-bolts are cheaper and more common too...

A........

[Chevy1TonFun]

I have a Dana 70HD Dually rear-end. The spring perches are at stock width. I will measure is tomorrow if you want it. I can measure anything you need from the axle. As far as the weak pinion I disagree! For anyone that has seen a dana 70 pinion, they would know that it is much stronger and bigger that a dana 60 or 14 bolt (sorry diesel eater, not bashing you).

[JeremyPenner]

I'm a 14 bolt fan thats what we run in most our rigs, they are cheap and easy to get replacement parts for... the only thing i can think of is ratio options.. u can go lower with a dana.

[Blazer1970]

Before 2001, 14 bolts were used in cab and chassis 4X4s, and D70s were used in the duallies with the wide fenders. The cab and chassis duallies had a narrow rear end where the outside of the outer rear tires were about the same width as a normal single rear wheel rear end. The D70s are wide so that the inner tires will sit in the normal inner fenders with a bed on the truck. Two totally different width rear ends. Which width do you want?

[fun in dirt]

Originally Posted by Blazer1970

Before 2001, 14 bolts were used in cab and chassis 4X4s, and D70s were used in the duallies with the wide fenders. The cab and chassis duallies had a narrow rear end where the outside of the outer rear tires were about the same width as a normal single rear wheel rear end. The D70s are wide so that the inner tires will sit in the normal inner fenders with a bed on the truck. Two totally different width rear ends. Which width do you want?

This is exactly what I was thinking.
14 bolt = cab & chassis
D70 = dually (with hips)

[FormerMember]

Originally Posted by Ridin' High

I have a Dana 70HD Dually rear-end. The spring perches are at stock width. I will measure is tomorrow if you want it. I can measure anything you need from the axle. As far as the weak pinion I disagree! For anyone that has seen a dana 70 pinion, they would know that it is much stronger and bigger that a dana 60 or 14 bolt (sorry diesel eater, not bashing you).

14B has a third pinion shaft bearing, where the Dana design does not. This prevents the pinion from deflecting, causing the pinion to skip (and break) teeth under load (common on 70's). Sorry, the biggest 70 pinion is not much bigger than the 14B. The shaft size is pretty close but those rarely break regardless. They also have several sizes of Dana 70's (some use 60 parts), but I am talking biggest 70 to Corp 14B.

This is why the 14B has a stronger pinion.


I am happy to provide pictures if you like, once we get our net connection and power back. Not about to post pictures on dial up and a generator.

[DieselEater]

Not offended here......Everyone is entitled to their opinion.

I'm basing my opinion on the truck pulling we do.....When you have a 700 HP solid roller Big Block hooked to a 60,000 pound sled and floor it!!!

General consensus in the pulling ranks state my remarks to be true.

Here's a link to some of my vids with a stock 14-bolt....

http://www.youtube.com/TeamFRANKENSTEIN

A........

[FormerMember]

You can also add Single Rear Wheel hubs to a Dual Rear Wheel housing and get WIDE... or the reverse.

Basically, you can swap hubs onto a housing to get three separate wheel mounting surface (WMS) to WMS on a 14B.

I've broken pinion teeth on a stock 70U, never on a 14B.

[Dooley]

In dual wheel applications I prefer the Dana rearend and in single wheel setup the GM 14 FF.

[pulltilbroke]

Go with the 14b

Dana 70s are weak and like to break the pinion

I'm a truck puller don't ask how I know