Is there any adjustment on a 1998 Dodge Durango gear box?

Answer 1

Assuming you're talking about the steering gear box, yes there is. On top of the box toward the front is an adjustment screw. It consists of a metric Allen head plug inside a nut (18 or 21mm, I don't remember exactly). The Allen head plug adjusts preload on the input shaft bearing and the nut around it locks it against the gearbox housing to hold it in place.

To adjust: Have the engine off and the steering wheels straight forward. Loosen the nut on the outside of the Allen head screw, snug the Allen screw GENTLY, then hold the Allen head screw in place and re tighten the nut to lock it down.

Keep in mind that any other component in the steering system can cause excessive play, so if this adjustment doesn't resolve the concern check over all the tie rods, drag link, rag joint, etc. to verify nothing else is worn.