Could my wheel balance be so off as to make the truck shudder so violently starting at about 40 that I can't control the truck? And would it have been masked by a steering stabilizer? It wasn't there until I pulled it off the truck to see what it revealed, now I want to fix it, not just hide it.

my cruiser was the same way, not enough caster due to lift shackles in the front. It was ok with the steering stabalizer on but once you took it off you were in for the ride of your life!

solution is that it most likely needs more caster

balence the tires just cuz. Check the tie rod ends, knuckles and wheel bearings. Also look at spring plates and shackles. I had a hell of a wobble for a long time in the 62. It turns out the DS knuckle cap was loose.

Yeah, I'm slowly working my way through the whole front end. All the rod ends seem fine, its aligned pretty close to straight. I'm kinda leaning toward incorrect bearing preload, but we'll see.

Mine did it because of caster. It was only off like 1* or so but it made a world of difference. It was simple for me to find the problem because every piece on the axle was brand new. The tires were brand new and balanced perfectly. It was surprising to find how much difference the caster made. Oh, it also made it nearly impossible to flat tow the thing because it made the wheel want to flop to either side all the way. Most of the time if the wheel balance is that far off it will cause problems from start, not just over 40.

do you think a steering stabilizer would hide it though?

I think the stabilizer might have masked it but if it was a drastic change once the stabilizer was gone than I would think you have more than just the caster causing problems. Is the problem in the steering wheel as well? Is it hard to control because the wheel is shaking or is just the vehicle flying all over the road and the wheel is not shaking?

The change came as a result of removing the stabilizer. There was slop in the steering, but that has not changed. The front end goes crazy, but the steering wheel really doesn't move, because of the pre existing play. So instant loss of control. In any case, shims are on the way to see what that does for me, and I'm gonna double check everything I can get to easily, then start tearing things apart.

I have a Land rover and am going through the same thing right now. It shakes at high and low speeds not all the time but intermitent. LC's I think have the same type swivel ball front end as rovers do. So far I have put on new suspension, new bushings, new steering dampner. I should have checked the swivel pre load first as well as ballance the wheels. Next week I am going to replace the front bearings and have the wheels ballanced. Oh I also replaced a bent tie rod and all new steering ball joints and still get the death wobbles. I need to check toe in again this week also.