I have a 2005 GMC Sierra 1500 with a v6 and a 5 speed manual Transmisiion.When Shifting from any gear I get a clunk.When in 1st and moving at low speed makes a noise like ball bearings dropping or better yet like a diesel.For the record its not a diesel.

Is your clutch pedal spongy if it is a hydraulic clutch there will be a small resivoir on the fire wall next to the brake master cylinder,if so check the fluid level,the noise your describing sounds like drive shaft u-joints,or cv axle drive shafts in front if its 4 wheel drive,block the wheels and put the truck in neutral,to release any tension on the drive shaft,go underneath,grab the driveshaft a foot behind the transmission,and push up an pull down on it while observing the u-joint in front of it if there is any looseness or play it is damaged,any movement up and down or left and right requires replacement,do the same to the other end at the rear axle,the rear axle u-joint is the most common failure,but check them both,