93 W250 Shift linkage?
 

I just got a 93 w250 Cummins with an auto trans and and toggle switched OD. My question is, is there any way to adjust the linkage for the trans or anything to get the gear to line up with the indicator and actually lock into place. The trans was either rebuilt or replaced. Essentially whenever my tires slip and then rein-gauge the trans slips out of Drive and into Neutral.

Any help appreciated

Theres a cable-hook assembly in the dash cluster that can be shortened or lengthened by using the hook in different notches on the indicator strut.