Working on this 1977 Dodge W100 with a factory installed np 203 transfer case. The speedo is 20km/h (12mph) out (low: reads 80km when going 100km-ish). The truck has 3.55 diff and 31” tires. Reading all I can about these np 203 units - I now suspect I’m going to find that it has a 7 tooth (red) speedo gear currently in the transfer case and I assume that I need to track down a 5 tooth to replace it with. I only assume this because the 7 seems to be the most common and the only other version I’ve seen for the dodge application of the 203 is the 5. I’m probably way out this so any help would be appreciated- if you’ve also been down this path.
