Need help with this noise!

I have a 94 Chevy Suburban 4x4 2500 with 93k miles on it. I'm new so I don't know how to describe sounds in writing, but I'll try. I'm getting a "groany, with inconsistent little thumps, and sort of grindy" noise when going uphills. The travel uphill is sort of grindy as well.
On the level, I don't seem to notice it that much, but as soon as the vehicle goes on any sustained hill, the noise starts to be pretty audible and is quite apparent. After the hill, the noise subsides but comes back the moment the gas pedal is pressed and sort of goes away the moment the gas is taken off. This lasts for a long time.
It seems to be worse if the vehicle has been sitting out in the cold. The noise changes if the vehicle bounces due to undulations in the road.

I would really appreciate any help
Thanks

You might take a look at the front axle constant velocity joints. Check the boots for sure. If you've got any rips of tears that could be a problem. The joints could go bad even w/out ripped boots.

You say the noise only occurs going uphill so it sounds like a powertrain problem. I wouldn't suspect the front end unless it happened all the time. Have you checked all your fluid levels in the powertrain such as trans, and differentials (front and rear-but I doubt front).

Thanks for the reply...
I have checked the CV joints in the front for tears in the boots. They seem to be Ok. I have also checked transmission fluid and Diff fluild. Both seem ok.
Other suggestions most welcome

I think you are right, it seems to be a power train related issue since the noise is only evident when either accelerating or going up a hill. Could it be associated with bad universal joints or even a bad wheel bearing?