Ok I have a question but first let me just tell you what I have done . I took an engine out of a 1998 holy grail and replaced it with a 1996 12 valve cummins and I was told all I had to replace was the oil pressure sensor and the power steering pump but I wound up changing a little more than that like the mounts and the throttle mechanism on the pump . I put the engine in and I have had a problem with the alternator not charging and the rpm gauge not working so I replaced the cps and set it at .050 . That didn't fix the problem but the rpm gauge does jump up when I first crank it then back to nothing . I took it to a mechanic with all the tools that dealer has to check PCM and he said PCM was bad cause it wasn't reading that it had one . So I had the PCM sent off and they had a hard time with it but they got it fixed and got it flashed and sent back to me they said they had a hard time flashing it . Anyway after all this I got the PCM back and hooked it up and no change . So I got to looking at the harmonic balance that came off the 98 12 valve and it has 2 notches in it and the one that's on my 96 has one stripe of reflective tape on it . So could this be my problem ?

 

Never mind that didn't solve the problem either

 

You definitely need the 2 notch balancer...........

Time to start checking the wiring from the PCM to the ESS and I think that is where you will find your problem.

BTW, the 96 should have also had a 2 notch balancer and the mounts should have been exactly the same as your 98.......

 

Pat.
In '98 Dodge goes to a motor mount that bolts on with 4 bolts rather than the 3 bolt motor mount that bolts onto the earlier year 12V blocks.
I am sure you could use either or, but they are different.

Edit:
I just checked a '98 12V at my house and it has the three bolt hole motor mounts.
Since it was a quick fix to throw the 12V in for the first three months of '98, I bet they used what ever mounts where on the shelf.

 

Cool, I learned something today. I never gave the bolts to the block a thought, I didn't think Cummins would be crazy enough to change that.......

Perhaps they did the change with the 24V production since it was only a few months into the 98 run?

In any instance, good to know!