I just bought a 1996 Trooper. The rear differential is howling. I discovered it has water in it. The ring/pinion are obviously shot. Id like to look for a used pumpkin (is that term still used?) before I remove the old one that's still working. Does this plate tell me what the ratio is and and if it has positraction? How do I decode this? Is there another way to get the specs on this vehicle?