Check the DIY FAQ section above ..Throttle Valve Cable (tv cable).....shift rod linkage, with the lever on the tranny fully rearward (park) adjusting block should be centered on hole. If the shift rod is sloppy there's a grommet at the top of the rod that will need replaced first. Lubricate everything....

 

Ok so the linkage all looks good. Looks like it was replaced not to long ago. The bushings all look new. But I did take the truck to a transmission shop and they said its most likely something to do with a snap ring on the overdrive unit.. I was wondering how hard is it.to get To this snap ring or how to service the over drive unit???