95 2wd Ram Overdrive noise

[km5bq]

Hi, all. I'm new here. Been looking all day to see if anyone knows anything about this:
95 ram 2500 2wd 5.9L 46rh 300,000 miles. runs good, consistently good shift quality but makes noise (somewhere between a whine and a growl depending on speed) when the overdrive is engaged. The pitch follows wheel speed. The noise ceases (or at least greatly diminishes) when the od disengages, as when deselected by instrument panel switch. The noise starts as soon as the overdrive begins to engage, i.e. at the beginning of the shift underlap. I replaced the overdrive piston clutch last night, as nothing else made sense to me. This had no effect whatsoever. A salvage dealer told me nearly every 46rh he's seen fail has had an overdrive failure, but couldn't tell me what was failing in the overdrive. I agree a full teardown is in order, but need an idea of what's going on, as I surely will need more than an overhaul kit, and I only have access to a well equipped shop on weekends when the parts house in closed. Anybody have any thoughts on what fails in these overdrive units? THANKS!!