Um, I think I may have figured it out. The new transmission is a 99, and the wiring harness is a 97. So I guess it won't shift because the harness doesn't have a hook up for the speed output sensor because the 97 isn't designed to have one. Now what do we do? We bought the other speed sensor on the differential, that should make the speedometer work, but what makes the 97 shift? Are the PCMs the same in these years? We have come this far, i would hate to give up now!

 

The 99 is the one that does not need the output speed sensor on the tranny. The one on the rear diff will not help the speedo or the shifting.

 

Is there a way to make this setup work effectively?
It will be hauling around 4500 lbs regularly.

 

You need the correct sensor on the tranny first of all. Did you do that yet? Did your factory harness plug into the tranny everywhere else?

 

First of all, thank you everyone for helping. We replaced the speed sensor on the tailshaft today and it started shifting at around 3000 rpms. So we adjusted the TV cable a little, and now it shifts at a little over 2000 rpms. We cleared the codes on the obd II reader, and it only reads p0500, the other speed sensor on the differential. We have ordered that, it will be here tomorrow. Hopefully the speedometer will work after that.