Need help id rear end

[Roachgod]

I have a 79 1ton that came with a 454 and a 4spd with the granny gear. I had people tell me its a dana 60 and others say its a gm14 bolt. how do I tell which one and what ratio?

[b454rat]

Could be a Dana 70 or a 14ff. If it's a Dana axle, it will say 60 or 70 on the bottom right of the diff cover, it's stamped into the webbing. A 14ff will have a lip on the bottom of the diff, kinda hard to explain. Here is a 14ff.
[IMG][img=http://thumb12.webshots.net/t/60/160/5/13/17/2373513170043830172OCUTUw_th.jpg][/IMG]

[GMC1tondually4dr]

Count the number of bolts holding the rear cover on.
10 bolts would be a Dana 70 or 70HD
14 bolts would be a Corporate 14 bolt rear.
The Dana 70 is the stronger of the two.
Check the web connecting the tubes to the housing, a Dana 70 or Dana 70HD will have a 70 or 70HD in raised figures.
A 1 ton should have a Dana 70 or 70HD.
A 3/4 ton should have the Corporate 14.
Both come in a full floating arrangement.
I have a 1ton ('86 Crew Cab Dually) and a 3/4 ton ('91 2500 Sub)


CCDually

[trkklr77]

73+ chevys never had rear d60 stock.

single wheel its a 14bff
dually wheel it could be either a d70 or a 14bff.

d70 cover looks just like a d60 cover and it will say d70/u on the lower right had housing web.

14b full floater will have a diamond shaped cover and 6 bolts around the pinoin gear.

[rfmaster]

My 75 C20 (3/4 ton) is equipped with 14 bolt (cover) corporate while Dana 60/70 use 10 bolt cover.

The best way to ID is too count number of cover bolts - Dana 60/70 should have 10 bolts in 9-3/8 by 10-1/4 semi oval configuration cover. Dana 60 was used in K30 77-91.

Measurement Id's
Dana 70 shares the similar cover design as Dana 60
Dana 70 axle tubes measure around 3-1/2" diameter. 60 is smaller ??
From center line of the axle tube to bottom of differential (eyeball)
Dana 60 ~6"
Dana 70 ~6-1/2"
If the cover is off measure ring gear diameter:
Dana 60: 9-3/4" with 12 bolts
Dana 70: 10.54" with 12 bolts

The other way is to look for mfg ID# numbers cast into web.

//RF

[Roachgod]

It has 14 bolts non dually so i guess its the gm 14ff. Please excuse my ignorance but what does full floating mean? Is that rear end supposed to be posi or could it be either way? The truck sat for about 13 years and i'm only getting one wheel peel. It only has about 70k miles on the truck but since it sat outside so long would new lube and maybe some additive get it to lockup?

[b454rat]

Could be a Govlok. If the tag is still in the glovebox, look for G80, that is the RPO for it. They can be picky when the lock up. One tire has to be spinning at a 100RPM difference. These rears are tough, change the fluid, check the brakes and use it!!

[rfmaster]

To roach

This generally a gentleman’s board so any technically related question is worth looking into. Enough said. A semi-floating axle (SFA) is very common on the rear of most trucks. SFA consists of an axleshaft on each side that is splined on the inner end where it mates to the differential and has a wheel flange where the wheel studs mount at the other end. This assembly is rigidly connected to the end of the axle housing using some type of flange arrangement. The axle shaft itself is supported with large roller or ball bearing out at the end of the axle housing.


Full floating systems (FFS) uses an axleshaft on each side that is splined at both ends or splined on the inner end and have a specialized drive flange on the outer end. The shaft is coupled and secured with the differential in the same way as a semi-floater. However, the outer end of the shaft is substantially different. The outer splined shaft slides into a locking hub or an internal splined steel drive plate that bolts to a hub cap, similar to what is found on a front axle of most 4x4. In either case, the axleshaft is allowed to float in the system, if the hub is placed into 'free' position. It should be noted that in FFS the locking hub support the weight of the vehicle, not the axle as in SFA.

I hope this helps

In regard to your truck - I would rip into this rear end- change all bearings and determine if it a posi or not. 13 years of sitting out in the pasture allows moisture to contaminate lubricant - turns milky white. If it is I would go through all bearings and clutches (if posi equipped) to make sure everything is in good working order.

[trkklr77]

full float means your wheel wont fall off if you break a shaft, the rotating hub is held on in the same way as any front wheel with a spindle and nuts. the shaft has no weight load put on it, only driving force. the axle shaft can also be removed without removing the tire or even lifting the truck off the ground.


rfmaster,"Dana 60 was used in K30 77-91. "

that is front axles bud.

14bff are flat out one of the strongest axles you can have in a pickup. but the gov loc is a picky weak link. i abused the piss out of mine till one day i was able to snap it trying to be the truck pull champion of the world. the gov loc only uses a 3Y shaped cross pin and the open diffs use a 4+ pin. the 14bff detroit locker can only go in the open carrier.

here is what was left of my gov loc. i do miss it now that i have an open diff.