Kraton Help identify awful noise

[Captain Blaster]

Can anyone recognize or identify this terrible clacking ratcheting sound? It sounds like gears grinding or something. You can really hear it most when it's accelerating. Coasting, sounds fine. And hanging, holding it, sounds fine. It almost sounds like when you pull off a long strip of duct tape.
Kraton 6s V5, two 3s batteries. Everything runs well, but something is wrong. I've taken apart all three diffs, checked and rebuilt and refilled all of them. (The front one had a broken pin on the sun gear which caused the housing to wobble and get scraped by the input gear; I was so sure that was it, but the noise remains. )
Could it be the pinion? It doesn't look too worn to me. And it only sounds bad under acceleration.
Thank you!!

 

[Garcbomber]

Time for aluminum cups and rebuilt diffs. Sounds like you went a little more than 20 packs before maintaining them.

The output inserts have probably separated from the composite creating a planetary disengagement. Or upon rebuild you lost shims on the input or ring gear side.

 

[Captain Blaster]

Time for aluminum cups and rebuilt diffs. Sounds like you went a little more than 20 packs before maintaining them.

The output inserts have probably separated from the composite creating a planetary disengagement. Or upon rebuild you lost shims on the input or ring gear side.

Ok. Thank you. You're probably right. Do you have any recommendations for Aluminum cups? You mean the diff case, right? Arrma? Hot Racing? I do have some M2C outdrive cups on the way right now, that will be nice.

 

[Captain Blaster]

Found the culprit. Worn input gear.

 

[GreatWhiteDope]

Glad I stumbled across this post. Mine has been sounding very similar as well. I think I forgot a shim when I opened the rear diff up. But now I’m definitely going to check my input gears