360 46RE driveline swap, wont shift

I finally got the Duster out on the road last night only to find that it wont shift.
While I'm digging back through the service manual today, I figured I'd get everyone's feedback on what it could be.

The driveline is a 99 Dakota 360 with the factory efi still in place, a 46RE ( 8pin plug ) from a Dodge RAM.
Symptoms:
When in drive it will shift into second some of the time, but will hold 1st for a long time.
Will shift from 1st to 2nd when manually moving lever from 1 to 2 but will not shift into 3rd when moving lever into D from 2.

I've replaced the output speed sensor but the old one ohm'd out the same as the new one. I've also adjusted the TV cable numerous times.

I'm wondering if I cut something out of the harness that is needed.
I don't have any history of the trans other than it was working fine when removed from the truck and it'd been rebuilt less than 10k miles ago.

What do you all think?

UPDATE:
I've been reading around and found some possible causes, but I'm going to have a hard time diagnosing some of them as I don't have the ODBII connector wired in.
Could be solenoid pack, 8pin connector issues among other things. I'm going to install the electric speedo drive unit tonight and see if it needs the output from that to be able to shift it because it shifts from 1-2 manually.
If time permits I'll start checking the wiring....ugh...