Driveshaft Differences?

[Alex V.]

I'm still hunting down a vibration in the '67 'Burb's driveshaft - looks like the front shaft is bent through the middle, so I'm looking for a used one or will have a new one made. But first, I need to determine if my DS is a stock piece or if it was custom made/shortened.

The 'Burb (2WD 1/2 ton) was originally a 3-on-the-tree but was converted to an NP435 4-speed before it came into my family. I've seen several late 60's 1/2 ton trucks with the driveshaft that utilizes a movable carrier bearing and the slip yoke in the end of the transmission - however, my DS is made from larger tube than those shafts, has a rigid output on the trans., a rigid carrier bearing, and the slip yoke immediately behind the carrier. I've seen pics of a few shafts of this style, but none were in the truck so I don't know exactly what it came in. Therefore, I'm not sure if my driveline is part (or all) custom, or if it's all heavier-duty factory parts that the PO bought over the counter for the trans. swap. What can ya'll tell me about which DS was for which application? Dimensions for the different shafts would be great, as well.

[LockDoc]

Alex,

36 views and no answers. This is kind of a hard question to answer. Probably quite a few variations. My suburban is a '69 2WD, 1/2 ton and there is a yoke and U-joint at the back of the transmission, a yoke and U-joint just behind the center carrier, and a U-joint at the rear axle pinion. I don't think I have ever seen one without a U-joint at the back of the trans. Doesn't sound right to me...

Can you post some pictures?

LockDoc

[Bigdav160]

There is specification for driveshaft runout. I can 't find it right now but it's smaller number than you might think.

Describe the vibration. At what speed, what engine rpm, is felt in the steering or seat and what frequency. Buzzy or thumpy?

[67WrenchHead]

I grew up driving a 67 C20, camper special. Now have a 71 C10 Stepper (many, many, years later). Both had/have the 2 piece drive shaft, a total of 3 ujoints. In one of the factory manuals I have, it states the rear part of the drive shaft needs to be indexed 3 splines counter clockwise, looking from the rear end up towards the trans. There were 2 different specs, I think one was short wheel base, the other long. I thought this interesting, because every other slip yoke drive shaft (mostly 4WD) we always made sure the ujoints were in line or in "phase".

[68 TT]

That sounds like the configuration my 78 K20 had. You may have a modified square body driveshaft in there.

See if you can find one to take a look at to confirm this. Sold mine a couple years ago or I would take some pics and let you know for sure.