I believe , if not mistaken , the heating grid relays on a 91 Ram with Cummins are exactly the same relays as the solenoid that is used on a Western Plow. I had to replace one recently and the Dodge dealer told me Dodge doesn`t carry those solenoids anymore and I needed to find a SALVAGE yard to replace one I asked the guy again and he said " I TOLD you you would have to get one at a salvage yard. " Instead of bawlin him out for being so stupid, I hung up. Then parts stores seemed to not have it. I freaked. It was cold and would not crank it up without the heating grid! There sits the bread & butter, parked in the wind. So down to the junk yard and there was a 91. Pulled it off and bingo. Then my cohort exclaimed that the solenoid was exactly like the one on his Western plow. And it is. Amazing, these dealers. Thats like the fourth time different dealers have jacked me around in time of need. Need a good referal for Dodge truck factory parts or an outfit that will tell you if you can get it aftermarket.