[jwn301]

I just replaced the wiper unit on my '82 2500. Don't know the 31 well enough to know whether my solution will work for you, but mine is mounted with a standard 3-bolt pattern. Got it at West Marine for $70. Best part is the wiper arm shaft is 2-piece, so the length is adjustable. Blade is fairly short, but works perfectly for the starboard pane of my three-piece windshield. I don't know whether longer blades are available, but you could check with them. Good luck!