Hello Again!
Thanks for everyone's posts.

So, I think I may have some transmission problems (per eariler post)

But, what do you folks think about this: Serious vibrations in most gears, especially Third, Forth, Fifth. Let off the gas, vibration gets much better, almost stops, or put it in neutral at the same speed and the vibrations gets much better. So I have an extreme vibration that nearly stops when I am not giving it gas in gear. If I rev up the truck in neutral while moving, no vibration. Down hills in gear, less vibration.

Is this also a sign of a failing transmission? To me it makes sense, but I don't think I have heard of this before.

 

I'd check motor and transmission mounts, too..but it definitely sounds like it has something to do with the power train.

 

double check U joints just to make sure thats not an issue..

 

it does sound like the uj's

 

Yeah had a similar problem- was the u-joints

 

i had the same problem and it was vibrating so bad my muffler fell off. i decided to drop the drive shaft and saw the problem. my rear u joint was all messed up. i put a new one in and it now rides soomther then ever.

 

Thanks everyone. So I finally unlocked my hubs (it is really snowy where I live), no vibration. I am thinking front driveline. ujoints seem to be fine.

Also, if it is a front driveline, cv joint issue, what can I do? Where would I find a new front drive line other than a junk yard? None of my local junk yards have any first gen parts.

 

Ujoints, driveline bolts, or that big nut holding the plate onto the dif. input shaft.

Get under the truck (with the truck in gear, the e-brake on and the wheels chocked for gods sake!), and give the driveline a good shake and twist. With the truck in gear and chocked, there should be very little play. If it moves quite a bit, or you hear clicking or thunking noises, start troubleshooting the driveline. From your description, this only occurs when the driveshaft is engaged, so this is a good place to start.

For more info on this, you can do a forum search here for "driveline vibration", and bask in the glory of the hundreds of posts worth of information.