Now , is that picture taken under your slide ; or do we both own a 2000 Dodge Caravan ?
Rack and pinion slide drive will use two slide supports under the slide with the tooth drive on the bottom .
In the coach basement , between the two supports will be a torque transfer shaft between the front and rear pinion gears .
I believe that National used a ; Power Gear slide drive ; and the transfer shaft will have bolts between the shaft and the pinion gear . You probably have sheared off one of the bolts , between the square shaft and the round pinion axle shaft .
You'll have to get crawling around and check out the drive mechanism from the motor to both pinions.
Missing bolt would look something like this picture of a Monaco slide drive , red arrow shows where a bolt should be .
I have a Power Gear slide drive parts pdf ( too large to post in the forums ) I'll look through for the bolt specs.