To start, I already know that shift motor, wiring, or the electric switch on the shifter are the most likely failure points. It won't shift even with the motor removed from the axle, otherwise I would have just locked it in high range and moved on. Truck is a '59 B-162, electric shifted 2 speed rear end, that has never fully completed a shift in to high range. Once it almost made it there, got about 500 feet before I lifted off the gas, and it disengaged. While I know there isn't a true neutral in the axle, it always felt like it would get stuck in a neutral between low and high ranges, then was a bear to get it back in low range and driveable again (took a bunch of shifts back and forth, between 1st and reverse gears, to get the thing to slide back into low range...otherwise letting the clutch out felt like the transmission was in neutral). At one point I found it would hold high range in reverse, but never in forward. About a year ago, assuming that like most, it was an issue either with the switch, motor, or limit switches, I pulled the shift motor off the axle, and attempted to shift the axle into high range manually, and couldn't get it to go into high range that way either. It would _almost_ slide in, but when turning the driveshaft, the shift fork would kind of ratchet. Usually I could get it to hold high range while spinning the driveshaft in reverse, but would ratchet in forward. I then pulled the center section out, moved it to the garage, and forgot about it for a year. I got ahold of the Eaton factory service manual some time ago for these axles, and it mentioned inspecting the sliding clutch and planetary assembly for excessive wear, but didn't really show what excessive wear was. Today, I pulled the differential apart for inspection of the sliding clutch, and mating planetary assembly. I found that again, if I rotated the sliding clutch while pulling on it, it wanted to ratchet around rather than engage as well. The harder I pulled on it, the less it wanted to slide over and engage. I've tried to find pictures of these parts online, but haven't been able to find any kind of close ups to compare new parts to mine, or anything showing what excessive wear would be. So, are these two toast, or should I continue to look for issues elsewhere? I know that the splined parts aren't suppose to be a sharp square cut, but given that one side of the planetary splines are much more worn than the other side, I'm thinking that's where the issue is, and would explain why it seems to be grabbing in reverse, but not in forward.