Truck makes a clunk when intially put into gear

the "backlash" felt by reversing the drive shaft direction is normally the clearance in the spider gears in the diff so to get rid off that ( not necessary unless it is excessive) is to pull the diff center out and fit new thrust washers behind the spider gears
next check the diff mount bushes as the diff reaction will move the bolts in the mounts and make the noise

If it is a four wheel drive check your tail shaft or drive line by securing the vehicles front wheels jack up the rear tires and in park try to rotate the drive line if you can hear the transmission sound like it is going into gear the transfer case could be damaged! If not a four wheel drive pull the transmission dipstick and look to see if the fluid is dark red or metallic grayish color if so then you're clutch disks inside the tyranny have been worn out and it needs to be rebuilt!

I'd look at the transfer case first.

check unversal on drive shaft. put in neutral and shake drive shaft

the noise is the free play in the side gears of the diff and is normal in a diff that has some miles
there is a problem if the pinion moves forward or back when turning the shaft
check for "U" joints as if they are failing you will get the noise when changing direction
other areas to check are suspension rubbers and transmission rubber mounts

sounds like your clutch is going out, is it hard to put in gear with clutch all the way depressed? could also be the sinkronyzer going out, could be the gears in the transmission also going bad. need to check the fluid in the transmission.

Is it a metal shaft? When you put it in drive does it make any noise? Does the speedometer move? Does it make a loud clicking sound when you put it back in Park?

When you put your car in gear. The engine will move slightly.
Check your exhaust is not banging on the body. Give the tailpipe a good wiggle.

Turn off engine . get the vehicle on level ground. try to move driveshaft back an forth or,by rocking in twist motion,,, try to hear a knock,,,this would indicate a worn universal joint.either front or back, if you are good enough to discern which one is making the klunk, change both to be on the safe side. think they may be about 20 dol apiece.

Hi Ali,

This sounds like one or more of your motor/powerplant mounts is broken. Here is an easy test:

Have someone sit in the driver's sear with engine running and trans. in Park.
You stand in front with the hood open. Have them shift from Park to Reverse, and then Drive and back to Reverse and Park, taking time to stay in each gear and give some throttle while holding the brake pedal tight. This will rock or move the engine a certain amount as they shift through the gears and apply power lightly. It will move alot more violently with broken mounts.

If you have a clunking noise on Reverse shifts, you should be able reproduce this with the hood up and pinpoint the noise and/or sight the faulty motor mount with a friend's help. Good luck, I hope this puts you on the right track to fixing this annoying noise.

Sincerely, Tater Todd