1983 4x4 having severe shake issues

[Greasel]

Hey there! I did a quick search before I joined up and was not able to find the answer to what my issue is here, but I'm sorry if this question has been asked too many times before!
Ok, so I have a 1983 toyota 4x4 with a small shackle lift and some slightly larger tires. I purchased this truck as a non-runner, as it still needed some brake components before it could move. After I fixed it and all was said and done, I went for a test drive and this thing shakes really bad. The funny thing is that once I take it out of gear the shaking stops completely. a friend suggested that it could be lockers, so I inspected those...and that was not the issue, he also thought it may be stuck in 4 low? although the stick to change the gearing is free and is not stuck...

Anyway, I'm looking for some suggestions on what this might be! Thanks very much. Any help well be very much appreciated.

[bbagwell]

I would check the motor mounts, and transmission mounts, and u-joints.

[ryan]

I had a bad shake in by 83, and it ended up being the carriage bearing for the rear driveline.

[BigDaddy]

I would make sure the hubs are unlocked, and the front shaft is not moving. Then like the others have said start to look at driveline problems. I don't think it’s a bent shaft, it sounds like power has to transfer to the driveline to make this happen.

Is it a 4 speed or Auto? If its a 4 speed play around with the clutch and see when you start to get the vibrations if it keeps doing it with the clutch pressed in then I would say the bearings or something along that line. Just a guess. One more thing. Remove your Rear drive shaft, put your truck in 4 hi and make sure you lock your hubs in, drive down the road to see if you get the same problems? I don't think you will, and that will give you a chance to inspect your drive shaft.

[Greasel]

Thanks for the helpful replys, Especially BigDaddys! I will be sure to try that driveline trick. I'm very curious to see if a gear/bearing has gone bad.
One other thing I noticed is that even when traveling at speeds of less than 5 MPH while in gear, you can feel something in the front end make a "Thump" that reverberates through-out the whole truck, especially in the steering wheel. Lockers are fine, nothing is bent. Seems strange? The symptom decreases when you push in the clutch, but it does not completely go away.

[fourwd1]

Is it a 4 speed or Auto?
They didn't have an auto trans in 83.

Put the entire truck up on jack stands and start checking wheels, driveshafts, etc while a buddy works the controls. Start in 2WD and make sure it actually is in 2WD (fronts shoudn't turn). If the vibes are present start looking closely, could be an out of balance or bent drv shft, bent rim, loose/bad pinion or t-case output, bad u-joint(s), loose drv shft bolts, etc.
Then go on to 4Hi and check the front.

[MudsharK]

Im not sure if this is relevant but what the hell...I had an 88 grand am 5speed with a replaced clutch and it would shake like crazy unless I almost rode the clutch. From a dead stop you'd have to just GO and not gradually speed up. I was told possibly the flywheel was bent or maybe harmonic balancer...never bothered to get it fixed, just drove the snot out of it. It kinda sounds like the same problem maybe? Anyways cheers and good luck