I have a 69 f250 with a 360,2wd,4spd.and a 2 piece drive shaft. When I start the truck moving from a stand still,unless I feather the clutch,I get a real sharp pinging type noise?? It sounds like a metal on metal ting?? I can't seem to diagnose it. Its not exhaust or anything obviously visible,and it only happens under load,because if you jack the back end up and engage the drivetrain,there is no noise at all??Any advise at all would be appreciated! thanks alot in advance

 

Crawl under your truck, and tap both driveshafts with a small hammer. Not hard, just enough to make a noise. They should go "ting" like you describe, but one will be different than the other. They might not both respond that way.
If one makes the noise you are hearing, then something is striking the driveshaft - or the driveshaft is striking something.
If you can duplicate the sound on a driveshaft, check for a bad U-joint in the rear shaft, or for a bad carrier bearing, or both.
The driveshaft(s) might be cocking to one side because the carrier bearing is bad, or the rubber support for the carrier is bad , or a U-joint is bad - or all three.

 

In addition to the above, you might also look at your motor and transmission mounts.

If none of the above you might look at the insides of your rear end - I have never worked on the F250 rear, but sometimes a cracked gear or pin on the 9 inch rear will talk to you under load.

Sometimes you just have to wait for something to break to find it!

 

thanks for the quick responses folks,I will definitely check these things out.....although I really hope its not in the rear axle!

 

Rear axle would be the last possibility - noise from there is mostly a deeper tone. I mentioned it only because I am not sure just what a cracked gear would sound like with that heavy a rear end.

As banjo said, most likely is the rubber on your carrier.

 

Is the noise there when you slip the clutch without taking off?

 

Another possibilty where the three knuckles against the clutch basket have created a crack in the basket. Most baskets are the cheaper thinner gauge material. Check for dry crunchy failing needles in a U-joint. Throwout bearing failing and squealing on the clutch fingers? Clutch disk down to the rivets?

.....=o&o>.....

 

One more possibility-
If your differential yoke is slightly worn relative to the shaft splines, but the nut is tight, you can get a ping as torque is applied. Could happen with any other yoke/shaft, but in my experience it has usually been at the differential.

 

Do a careful inspection of the driveshaft where the yokes are welded to the tubes, 1/32" away from the weld is a weak area from welding. Look for a faint rust line in that area as you might have a crack starting. Also look at the yokes, had one crack and fail on the rear pinion that made a high pitch squeak going forward after reverse.

.....=o&o>.....