Need help identifying sloppy driveshaft/diff play!

I have what seems to be excessive driveshaft play. What I mean is, when I put the truck into gear there is an audible clunk and a jolt. I took the rear tires off today to do the brakes and when I grab the drum and roll it back and forth there is a lot of play before the driveshaft moves a little. Is this normal?
When I put it in neutral and grab the driveshaft to turn it, there is play where the two driveshafts are put together (where the support is. This is a long bed)
This also happens in gear.
I don’t know a lot about the drive train and any help will be appreciated.
Thanks in advance!

Ring/pinion and/or carrier bearing worn out.

Worn carrier bearings, pinion bearings, stretched chain in case. Most likely pinion. What differentials do you have?

High idle?

Bowtie-dad said:

Worn carrier bearings, pinion bearings, stretched chain in case. Most likely pinion. What differentials do you have?

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14 bolt SF

fast 99 said:

High idle?

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I’ve played around with my idle for different reasons and that doesn’t change anything

You need to isolate the slop. I’d pull the driveshaft and look at it and its components separately. If you’re seeing slop where the 2 pc driveshaft comes together it could be as simple as a ujoint or as complicated as the male/female splines of the slop yoke.

Around an 1/8th of a turn at the axle yoke is not uncommon, the movement will be greater at the drums. For the axle you are feeling a super small amount of play between the ring & pinion, then play between the differential spider gears then the side gears to the axle shaft splines and then •possibly• play at the drums fitment on the studs - by the time you add all that up it can appear to be a lot when it’s actually normal.

An aftermarket locking differential can add a lot of play to the assembly.

I’d look hard at the driveshaft before worrying about the axle.

Pull the rear half or the front half or both?
I’ll get on it today.

That's a strong axle. I believe the backlash is supposed to .005-.008 inch. That's what I always set mine to with the 4.10 carrier. You can check if the cross pin is worn which would result in carrier replacement. Lift one side and rotate the wheel back and forth with the driveshaft hooked up. There should be very little movement before the driveshaft starts to move

Bowtie-dad said:

That's a strong axle. I believe the backlash is supposed to .005-.008 inch. That's what I always set mine to with the 4.10 carrier. You can check if the cross pin is worn which would result in carrier replacement. Lift one side and rotate the wheel back and forth with the driveshaft hooked up. There should be very little movement before the driveshaft starts to move

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This is where the problem is then. I have quite a bit of movement when doing this

Next step is pull the diff cover and check the cross pin and the mounting area where it rides. If that's cracked or worn a carrier replacement is necessary but it may the spider gears needing shimmed. A nesting kit should have all you need. If a carrier is what you need, I use Detroit tru-trac. It eliminates the spider gears and works as a locker in forward and reverse. They're about a grand.