Is it normal for the ZF to make a "clunk" (for lack of better word) when going over speed bumps/humps?? Seems like whenever I'm coming off of a bump, the tranny just makes a "cha..chunk" noise, almost like it's loose.

I usually hear the same thing when I have the clutch pedal depressed going over a bump. Not sure what is causing it, but doesn't happen every time either.

What you are hearing is the result of normal drivetrain "slack" or "lash". Manual tranny drivetrains have more slack designed into them to to the fact that manual control is less consistent than auto. The slack is noticeable when tension is removed from the drivetrain (clutch) and the vehicle is going over bumps and dips which change the pressure/tension on the drivetrain. I used to have very loud noises going down an off-road mountain with many rocks, bumps, and holes with the clutch pedal down and my other foot on the brake pedal. Eventually it impacted the driveshaft carrier baring and suspension. I finally found two ways to avoid this problem. 1) depending on road, leave the clutch engaged and use the brakes to control the speed. With a diesel this is a little more difficult depending on speed and gears. On the mountain I would downshift to 2Lo and this worked most of the time. 2) If you need to release the clutch, shift to neutral also and use the brakes at the same time. This is the most common, preferred solution and can be used at most any speed and 4x4 gear. This disengages the engine from the rest of the drivetrain and eliminates this problem.

good luck.

Yup! With an auto, the driveline is usually under load, either against the brakes or the weight of the truck and that keeps the driveline tight.

If i am going over some bumps, not all, with the clutch pedal depressed (mashed to the floor), mine does it also.

That's exactly the info I was looking for - makes sense.

Thanks