Update on KJ's truck/vibration problem

Thanks group. My truck is running, insured, and inspected. I however do have a vague problem, so I will detail all that I know about it.
1985' Chevrolet K5
305CUI SB bowtie power plant TH700R4 transmission - used from a 1983 GMC Jimmy NP203 transfer case - original
Recent Repairs: New front brake line, from proportioning valve to flexible brake line. New transmission cooler lines (too and from) Three new U-joints (both on rear axle, front on front axle) New: oil, tranny fluid (transmission and t-case), new oil filter, air filter, wipers
History of transmission repair: Last transmission wouldn't shift out of first, and was low on fluid when I dropped it. The pan was FULL of metal shavings. My guess is I found the reason why the first tranny failed when I finally found the source of the leak. It was an "obvious" leak and also well hidden in a pipe bend out-of-sight. I actually thought the cooler was plugged, and every once in a while fluid was coming up the fill tube and coating the passenger side engine compartment. Gary had described this, so I thought maybe I had a partially clogged cooler.
U-Joint repair: They weren't bad. I lost some needle bearings in the dirt from the rear drive shaft, so I just decided to get a new joint, then decided to change them all so I knew they were all good. They seated right, have all their bearings, and are full of grease. I haven't gotten the cardian joint apart, nor have I tried. The truck is currently a 2x4 only - no front drive shaft.
Carburetor repair: The carb is somewhat sorted out, it still starts hard (like the choke is pulled open too early) but it opens fully when running, so I don't get horrible gas mileage. Plug wires look good, haven't pulled the plugs yet though.
Wheels/Tires: The truck was supposed to have had new tires, rotation, alignment, and balancing all done by NTP (NPT?) recently before I bought it. There were a bunch of slips detailing all the work, and some receipts for things he had done (new fuel pump, the one on the engine). I didn't look too closely, so I don't know how long ago this was. I also can't vouch for his mechanical aptitude. I can always tell where he did some work…missing screws, different screws. When you have 3 bolts on a torque converter, and 2 different sizes………. That kind of thing.
However the wheels are a deep-dish mag design. The previous owner put acorn lug nuts on, (or just reused when he got the new rims) and just tightened them balls tight. Annoyingly, the lug nuts are not even all the same size. When doing a self-inspection of the brakes, I was able to get ONE wheel off- that's it. I tightened it back down, and later on that day I lost all my lugs and luckily not the wheel! Then it was explained to me why this had happened, so I didn't feel like ‘as much' of a retard. I've now seen the mag lugs with the shaft that's meant to go into the rim…. so now I know what I need to stop that from ever happening again. Right now, there just tightened balls to the walls…..However I suspect that the damaged rim might not be "self centering" the way it's supposed to. And here follows the problem.
PROBLEM: Vibration. I have a vibration from around 35MPH to 40MPH and from 63MPH(ish) to about 73MPH(ish). It doesn't seem to be coming from any one area, (front/back, left/right) but just EVERYWHERE…. The driver's side rear view even rattles…
My guess is a balance problem, since the problem reiterates at multiples of 2 (with a stronger intensity, and wider speed range). At any other speed, the truck doesn't shake at all. It doesn't pull off to any one side, stays relatively straight. It doesn't seem to effect "drivability" at all. I personally haven't put many miles on my tires, but I don't see any abnormal wear signs (yet).
BIGGER PROBLEM: I haven't done any driveline work of this kind, and only vaguely know how things work. And since I want to be the only one to twist wrench on my K5, I'll have to learn. Looking underneath the truck, I don't see any blatant problems, and one side generally looks like the other. I know there is A LOT more to alignment then "looks" though. So my question is: where should I start looking for the source of this problem? Does it seem like a balancing problem, and drive line problem, etc?
-The Lonely Grease Monkey 1985' K5 305CUI TH700R4 NP203 KJ's successor
"Ignorance is preferable to error; and he is less remote from the truth who believes nothing, then he who believes what is a wrong." - Thomas Jefferson
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pde_on snipped-for-privacy@hotmail.com says...

Step one when chasing down a problem like this is to fix what you know is broke. Namely the lug nuts. If it's damaged the rims, replace as necessary.
If that doesn't fix it, have someone follow you down the highway, looking for a bent rim or a tire out of round/blistered. If you have a vibration as low as 35, it's probably not balance. You could also put the car up on jackstands and run it to look for this. Be safe, make sure someone stays in it while running. Put it in 4 wheel, and just let off the brake. No need for any speed.
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Sorry, that is what I gathered from the NG's guesses. It may be totally wrong. It is not an all-time 4wd gear box, and it takes Dextron fluid. I think someone said it should be an NP208 in my truck? I am almost 100% sure it's stock, only because it isn't reman... the TH700R4 that came out was reman....
-The Lonely Grease Monkey 1985' K5 305CUI TH700R4 NP203 KJ's successor
"Ignorance is preferable to error; and he is less remote from the truth who believes nothing, then he who believes what is a wrong." - Thomas Jefferson
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As another poster pointed out, check your drive line. If you have a 'short' shaft, inspect the u-joints. Short shafts are prone to vibration. Look for 'Any' play in the u-joints. replace and balance, in that order.
Cheers

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Guess I wasn't clear enough. All the U-Joints running in this truck right now are brand new. I haven't had the shaft ballanced yet though.
-The Lonely Grease Monkey 1985' K5 305CUI TH700R4 NP208 KJ's successor
"Ignorance is preferable to error; and he is less remote from the truth who believes nothing, then he who believes what is a wrong." - Thomas Jefferson
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. . . KJ, see my reply in the chevy NG
flywheel bent.....
marsh ~:~
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