1986 Suzuki DT150 V6 won't shift into forward

[SD3CAPTRON]

I'm new to this so if I'm in the wrong place, please direct me to the right place. I have a Suzuki 1986 DT150 V6 s/n 1501-601824. This motor had a bad clutch in the bottom end and I removed the lower unit to repair it. I set the lower unit case in my front yard for a night and when I came home it had been stolen. I found a used lower unit in actually better shape on ebay and bought it. This unit needed a upper pinion bearing so I removed and replaced it. By the way if anybody does have this pinion bearing problem, it does NOT come out through the top of the lower unit as the Suzuki diagrams indicate but is a pressed in bearing through the bottom. I inspected all the components of the lower unit, replaced the seals and O-rings and reassembled according to the manual.
Here's the problem. When I have the motor running, it jumps into reverse on it's own. I have to "find" neutral with the shift lever, and it won't go into forward. I have measured all the shift linkage and according to the Suzuki manual it's correct. When I remove the shift linkage from the shifting lever that moves the shift rod down in the lower unit, it won't shift into forward. There are no adjustments on the shift rod, and the only adjustment I can find is on the "Shift clutch assembly" in the lower unit which Suzuki says "Never Change" that they're factory set.
Any Ideas from anyone, looking for help in Florida.