You do need to disassemble the trans, not just pull the VB and stuff. Test the soleniods with a multimeter
Inspect all the clutches and clutch seals
For some reason the 3rd sprag comes to mind

The reason behind the output shaft coming out the DS is the oil lube dam is on it and is likely to break if you remove it from the passenger side.

The clip on the output shaft 98+ shouldn't get removed, It comes apart and goes together like the axles. It'* a compression clip, not a have to remove E clip.

Following Andy'* thread about rebuilding a trans would be a great starter. Lemme see if the manual is online.

Looking over my ATSM and the P1860 code I had. It says Torque converter clutch pulse width modulation solenoid. It describes exactly what was happening. Disable shift adapts, inhibits TCC, inhibits 4th gear in hot mode. Hmm, what solenoid is that now.

Page 1 or 2 has the soleniod locations.

Does it explain slipping and the other issues? I'm optimistic that your problem is that small. And sure this transmission needs a full rebuild. Otherwise it will be out again....soon.

Looks like the TCC/PWM solenoid is the lower left one on the valve body.

I am going over all the hard parts. The 4th gear clutches are being replaced, new set on the way. I found no metal in the pan or on the magnet. Everything was very clean, even though it'* been 2 years sense I had it open. If the TCC/PWM went out that explains the problems I've been having for nearly a year. Sometimes when driving it would not enter 4th, even at highway speeds. Then shift out of the blue. I have 2 or 3 more solenoids here, so I'll be testing.

TCC doesn't explain slipping in 1st or 2nd. TCC is the torque converter clutch aka lockup. This only engages in 3rd and 4th over (I think) 45mph in your programming. If you look in HPT, you'll see where it'* commanded to lock and what percentage.

I'd like nothing better for this to be the problem, but it usually isn't the only issue.

If your torque converter itself is bad, you should see metal in the valve body bores (must disassemble to inspect properly) and in the little filters on the VB/channel plate spacer.

Your sending the tools I will need to pull the clutches right? Guess I'll be doing that next week. Really wanted to avoid that step. But if I must. I'll have to test all the solenoids, if I can find any tests in the manual.

I check the resistance on the TCC/PWM that is in my trans, 7.9 ohms. I have 2 others so I tested them, one is 8.2, the other is 8.3. The manual says 10-12 ohms @68*, but it'* only about 35* out there. That'* nearly half a ohm less. Changing it might be a wise move. I'm going to test all the others as well.

I tested all my solenoids. Keep in mind, the manual says 68*f, and it'* about 35*f in my shop, so the ohms will be a little less then what the manual lists.

1-2 shift solenoid, 18.0 ohms, manual says 19-24
2-3 shift solenoid, 17.4 ohms, manual says 19-24
EPC solenoid, 3.4 ohms, manual says 3-5
TCC/PWM solenoid, 8.5 ohms, manual says 10-12 (rechecked this one)

Looks like all solenoids are good.

Bring the soleniods inside and let them warm up, then test.

You have the ATSG book right? HEck..I'm calling.