1998 Mack RD Roll Door Panel

If you look in the door jam behind the lock is there possibly a metal strip about an inch tall, bent in a 90 degree angle, that can be pulled out? It releases the lock and a new one can be slid in.
Getting that assembly out is lots of fun. Been a long time and don't remember well enough to give instructions. Maybe tied into the front window track and vent window assembly, have to be loose for clearance?

 

If you push on door panel you can look for the clip or pin that release the handles, a auto parts store sells the tool that push back panel an pop handle off in one tool.

 

Try the rag method, I bought the tool, but since I learned this, I haven't used it. I'm pretty sure that you have a similar clip set up on your Mack.

 

Part of the handle is spring loaded. Push the part that is flush to the panel towards the door. There is a pin that holds the knob onto the crank. Push the pin through with a small nail or sturdy wire. The knob will slide right off.

 

Those Mack RD's sure are happy trucks!