M1008 Front Driveshaft Trouble

AFC1

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Hey guys- I am having some big time trouble with the front driveshaft in my 1986 M1008- maybe somebody could point me in the right direction here because I am at my wits end. I completely rebuilt a Dana 60 axle from lockout and lockout and decided to install it in the truck along with a Meyers plow push frame. While the axle was out, I remade all of the steel brake lines, new oil pan gasket,sway bar bushings, etc.... The original front driveshaft had severely worn rear U-Joints in it, so I decided to buy a remanufactured unit from NAPA. I received part number #93-1148 which was ordered for a 1986 Chevy K30 fullsize pickup. I received the shaft and it measured 26 and 1/8" from the center of the front U-Joint to the center of the rear most U-Joint. This shaft is about 4" too short. I figured that someone either wrongly packaged the shaft or someone had just thrown the wrong core in the box. I ordered another one..... same thing- way too short. After some brain-storming, I ordered a front driveshaft for a 1986 3/4 ton fullsize Blazer which is NAPA part number #93-1141. I figured the military would want some interchangeability in the field or something. I received the driveshaft and it is about 3/4" longer than the correct M1008 front driveshaft. I am now afraid of blowing my transfer case apart when I hit a bump. Anyone know where I can get the correct driveshaft for this truck???? Unfortunately, I turned in my original worn out driveshaft as a core when I recieved the first incorrect shaft. Now I am stuck with nothing. The yokes on both Dana 60s are exactly the same, I never removed the transfer case or transfer case adapter, what gives?? Any info/help would be greatly appreciated....
 

Recovry4x4

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Herein lies the problem. Civilian 1 tons (ie K-30) came with an NP-205 transfer case. That places the front output flange in a different position. Ordering the blazer shaft was a step in the right direction because it has the same transfer case as your M1008 however since it has the 10 bolt corporate front axle, the pinion is a little shorter. Since you are stuck with what you have, you should send it to a driveshaft shop and have it shortened a bit. Since it is a front drive shaft and hardly turns, it could probably be shotrtened at home, but it won't be balanced. FWIW the original shaft could have been rebuilt by a competent driveline shop. Hope this helps!
 

Recovry4x4

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You can also get a Front drive shaft from a 3/4 ton Chevy truck most of those came with a 208 T-case
The problem with these is that they are longer to compensate for the shorter pinion of the 10 bolt. Would be a perfect swap if you were adding lift to the truck though! The 208/ Dana 60F combo is certainly unique to the military D-30s.
 

AFC1

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Anyone have a good used M1008 front driveshaft for sale??? I doubt I will be able to get my original back as I sent it in a week ago as a core. Thanks for your help...
 

Fred_M1010

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I have a K10 truck from 83, which I've used as a parts donor for my M1010.
It's front driveshaft was identical to the one in the M1010
(The K10 was equipped with a 10bolt, TH700 and a Np208 )
 

Croatan_Kid

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The front driveshaft from a K30 with an NP205 would still work. By 1986, the NP205 was a 32 spline "round pattern" case and used a flat, 4-bolt flange just like on the NP208. I'm on my 3rd different trans/t-case configurations and used the same driveshaft and now, even with the NV4500/NP205 combo and 5" of lift with the front axle 1.5" forward of it's stock location, I'm still using the original front driveshaft.

I'm thinking it has something to do with the slip yoke. Were these driveshafts measured while they were compressed or extended?
 
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Fred_M1010

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I just measured mine from the M1010 as a reference.
When totally collapsed it is 30 3/4" from the rear flange mounting surface, to the center of the front U-joint.

The one from the K10, I cut up to use for my squaretube D-shaft build.
So I'm afraid I can't verify it's length now, but I remember checking that they where of equal length.
(I had hoped the one from the K10 would be longer, but it wasn't).

But on second thought, I can't guarantee that the one from the M1010 was stock, I guess it could have been swapped for a K10/K20 shaft by a previous owner...
 

Recovry4x4

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A fully compressed measurement can be misleading. Some slip and stub yokes have different travel. Ideally the slip and stub should be centered when the truck is at rest unless you have engineered limiting straps and measured the shaft open to that drooped measurement.
 

Skinny

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Just jack the right front wheel up as far as it will go and see if the shaft will go in without completing bottoming out. If it does, you are golden. It isn't rocket science with the length. As long as it doesn't bottom out at full stuff and run out of spline engagement at full droop, run it!
 

NVRENUFF

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If I lived closer I'd swap front shafts with you. Since my lift, the shafts could stand to be @1" longer just so there's more contact area.
 
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