i have a 94 s10 single cab, bodydropped 3.5 inches, and when im driving with the front up and the rear tuckin, at higher speeds above 50mph, the driveline makes a rattling noise, but if i press the gas or completely let off it goes away, but that period in between that, it rattles bad, it also happens when i have the front and the rear low, but if i have the truck all the way up, it doesnt do it at any speed, anyone have this problem or know what it could be?  

I dunno, but... does it sound like your driveshaft is hitting? like the cab? you would be able to tell if it was by looking at the driveshaft for "shiny" areas that are hitting...you'll be able to tell each and every spot.. cuz if it's not doing it aired up all around, but is with front up/back down...something to check for.
idea #2 - air it up to drive    

nope, im not hittin, i have a the cab tunneled, nothing hits at all, it just mainly sounds like there is slack in something until i put more power to it, its weird  

hmmm scratch that hahaha
how many miles on it? just curious  

define rattle??

rattle? like exhaust/exhaust leak?
vibration? u-joint?

if it doesn't do it all the way up, perhaps SOMETHING is hitting SOMETHING else when low/at an angle?  

it has about 90,000 miles on it, but we've replaced all the u-joints and everything and nothing fixes it, it rattles like you said like its hittin something, but if it was hitting something, it should do it at all times instead of when i just get on the gas or completely let off the gas, like if im driving and have a steady hold on the gas and i go down a hill and the truck speeds up, that noise starts until i give it more gas, beats me, but it sucks, ha, im tired of it, and only at high speeds it does it, if im cruisin at like 50mph or less, its just fine, just a little down hills  

when the drive shaft is in a straight line it will make noise.  when you step on the gas the pinnion angle changes same way when you let off of the gas the engine braking changes the angle.  if you can change the pinnion angle easy i would lower the angle and see what happens  

so you think its nothing to be worried about, its just normal for it to make that noise when you have a bagged truck? with the truck all the way up, the pinion angle is straight, makes no noise, but when i change by lowering the truck, driving low and what not, it does that between pressing the gas and letting all the way off, but when im low, i have to press the gas alot for it to stop makin the noise, but when the pinion angle is straight, its just fine, i just dont want to tear anything up, im hoping the noise is normal, well no noise is normal, but with a custom truck, its my first, just tryin to figure it out  

normal? I dunno about that, I mean, I wouldn't say just turn up the radio and forget about it, but maybe that's just me

what kind of suspension setup are you running?  

i would turn the radio up, but i can feel it in the pedal too, haha, but up front, a have strong arms upper and lower control arms, 2" drop spindles, 17" wheels, on airlift airbags, in the back, 5-link on airlifts, i need the slam specialties, i dont like airlifts, here's a better pic    

i have a bagged 99 s10 and mine did the same thing i had to adjust the pinion angle and i also ordered a custom driveshaft and now mine stopped making the noise  

when you replaced the ball joints did you mark your drive shaft so it went back in the same way.....if not your drive shaft could be out of balance  

Hello
Had a simular problem, you may have a 2 piece driveshaft(rod inside a tude)
The inside rod maybe broken, makes alot of noise at low speed, and out of balance at higher speed and rattling, replaced the shaft, all better. the old shaft looks fine, but rattles inside. hope this helps  

5569:
I dunno, but... does it sound like your driveshaft is hitting? like the cab? you would be able to tell if it was by looking at the driveshaft for "shiny" areas that are hitting...you'll be able to tell each and every spot.. cuz if it's not doing it aired up all around, but is with front up/back down...something to check for.
idea #2 - air it up to drive  

Hey there. You may have figured out your problem by now but I am 95% sure that at least one of your u-joints is going bad. My 96 Hombre was doing an identical thing & I only needed to drop the driveshaft & replace the rear u-joint. It was less noisey under load but would make noise when off the accelerator a bit or at certain speeds. Also with you are driving the truck at an angle sometimes this will also upset a u-joint with its life span have been shortened...

TC. Williams