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Help me identify my Dana 70 HD!

JeffHK5

JeffHK5

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I got a good deal on a Dana 70 at a parts yard but I'm not sure what it is.
With the diff on jack stands and the pinion pointed up it has 70-3HD on one
web,70-3HD/176A on one web and 42260/2 on one web and what looks to be
the Dana logo in the last web.Where I put backslashes read this as a second line. The ring gear has a date of 7/4/88 on it and axles have 35 spl. and are around 1.500 in dia. It's got a 73" wms to wms. I could not find anything stamped on the tubes. Sorry for the same old question but the Dana 70
is new to me.
Thanks Jeff
 
Sounds to me like a 70HD from a GM fleetside dually.
 
Look at the diff cover bolts, see if there is a metal tag bolted under any of them, sometimes there's so much grime that it looks like there is no tag at all. If you fid a tag, go to www2.dana.com, click on light axle, and then identify part number. That oughta tel you what it is. Sounds like a D70 HD for sure though. Pull an axle and count the splines, if there are 35, then it's most likely a 70HD or 70U. I have heard that the HD has 4" axle tubes that are the same diameter all the way out to the backing plate mounting flange. I have a 70U and the axle tubes are 3.5" and they neck down at the last 1" or so before the backing plate mounting flange. If it's a 35 spline D70, then it's a desireable axle, whether it's an HD or a U. Pull the diff cover and look inside also, you may have been lucky enough to have scored one with a Powerlok.

Geez, I read your post the first time around and totally missed that you already counted the splines. Sounds like a 70HD to me.
 
BlueBlazer62 said:
Sounds to me like a 70HD from a GM fleetside dually.
Click to expand...

I agree. The rearend is out of a dually pickup. Are you building a dually or planning on running Hummer rims? That sucker is wide.

Eric M.
 
Yep, Hummer wheels. All the #'s make me think that this a 70HD but when I mic'd the tubes there 3.5". I was told buy local GM parts house that this is a HD type 70 ,if it where a U type diff it would have the U marking on it somewhere and not 70-3HD on the webs.They also told me that it's a mith
about Dana 70 HD's all having 4." tubes. Don't know if this guy knows squat
about diffs but he was looking at a computer screen and reading stuff outloud to me.
Thanks Jeff
 
Seems like I remember there being something odd about 70-3HD's but I'm not sure. What's the gear ratio? Do you know what type of truck that axle came out of?

As far as I know all of the D70HD's that GM used had 4" tubes.
 
This rear has a 4.10 gear with a open one peice diff. It had dual wheels on it
when I got it and at a width of 73" it would have to be a dually. Inside of each spring perch is a larger pad that looks like whatever it came off had
one hell of a set of overload springs.This housing has 70-3HD all over it and not U once. I have heard that the only difference between the HD and the U
is tube wall thickness and O.D of some bearings?
Thanks Jeff
 
nvrenuf said:
Seems like I remember there being something odd about 70-3HD's but I'm not sure. What's the gear ratio? Do you know what type of truck that axle came out of?

As far as I know all of the D70HD's that GM used had 4" tubes.
Click to expand...


Good point. I'll have to measure my D70 HD housings, but I'm almost positive they are 4". I know they are considerably larger than the 14 Bolt FF which are 3 3/8". Wonder what the deal is with the "3" there?

Eric M.
 
Well I found my BOM# 605397, its a 88-91 only, dually heavy duty Dana
70-3HD. I saw some various posts on it on pirate and even though it's
very heavy duty most people stay away from it because of the lack of info
about what parts it shares with other Dana 70's. If I can get a Detroit locker
,4.56 gears and a rebuild kit for it i'm gonna give it a shot. Maybe i'm breaking
some new ground or something. Or maybe i'm throwing a grand in the crapper!
Thanks Jeff
 
JeffHK5 said:
Inside of each spring perch is a larger pad that looks like whatever it came off had one hell of a set of overload springs.
Click to expand...

This extra pad tells me its from a 88-98 style truck. I believe its just for the rubber bumpstop.

You will have to find out if you have 5/8" or 21/32" pinion offset before you buy gears & locker.
 
Dana 70-3HD

Thanks but I think I got it now. The "3" in 70-3HD is the note for the 21/32 pinion offset, which is not what you want. It does not allow for a lower gear than 4.10 , atleast not a Dana gear. I can get what a few shops are calling a custom gear , by custom they mean DAM HIGH PRICED ! Try 429.00 for just R&P! I'm now looking for a Dana 70HD 73" wms/wms with 4" tubes. Lucky for me I only paid 150.00 for the 70-3HD.

Thanks Jeff
 
I have a d70-3hd and I didnt know it either until after I built he truss and everything else. I set the gears up and found how hard it is to mesh. Now I have a loud coast noise which I am trying to find the remedy to it right now. some have said go with a ring spacer but I am having a hard time accepting that.

Atho I am sure I am correct by the Dana Expert site but here is mine. 605345-5 Mine shows to be a 3.73 but it had a 4.10 in it.

How do we measure to be sure of what we are dealing with?

Thank you,
 
merace19 said:
Why all this trouble to use a Dana 70 when the 14 bolts are every where?
Click to expand...

I just wanted to only look for dana parts. stupid reason but its what i wanted. I also liked the smaller narower housing but just as strong.
 
tjwrang said:
I have a d70-3hd and I didnt know it either until after I built he truss and everything else. I set the gears up and found how hard it is to mesh. Now I have a loud coast noise which I am trying to find the remedy to it right now. some have said go with a ring spacer but I am having a hard time accepting that.

Atho I am sure I am correct by the Dana Expert site but here is mine. 605345-5 Mine shows to be a 3.73 but it had a 4.10 in it.

How do we measure to be sure of what we are dealing with?

Thank you,
Click to expand...

If you have the old r&p you can use the part numbers from them to identify what pinion offset you have.

Gus
 
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