Hi folks! I have an older used 6x4 that has developed transmission trouble, possibly from towing too-heavy loads. It is chewing up belts rapidly, the driven clutch plates wobble, and it hesitates with a clunking sound under load.

In forums and on eBay it seems the most common replacement item is the driven clutch at about $260. I discovered that some of the drive buttons were missing and replaced those with a new set, but the symptoms continue. The primary drive clutch looks fine, the drive chains are in good shape, and I adjusted the chain tension per the manual. Does anyone have any experience with similar problems? What is the most likely diagnosis?