I just bought a 97 ram 2500 5.9 magnum truck. I had to put the dash back in and notice the obd2 port and wiring wasnt there at all. I have another 97 but 1500 same truck and gasnt the obd2 port plug. There's also a big relay right next to the brake light switch and the plug is missing also. Again my other truck has this plug but the 2500 doesn't why is it not there. The pig tail that they come out of has different plugs. The truck came from north Carolina so did it come from the factory that way

 

I believe 3/4 ton and larger trucks were exempt from obd2 until 98 or 99.

 

My 96 2500 has it.

 

So did mine.

 

As did mine and it was an early 96