this is probably a stupid question, but does it matter what way you put it back on in terms of the notches on each side of the counter weight. just want to make sure as this is new to me.

 

I ran into the same problem, I took it off without really looking at it. I figured it was internal balanced and just slapped it back on. It doesn't shake anymore than it did so either it doesn't matter or I got it right the 1st time. I don't think it matters but if it does you will know very quick.

 

It does not matter. The cummins engine is internally balanced the harmonic balancer is zero balanced.

 

Can this effect the rpm guage not working?

 

nope, its a "dumb" gauge and just counts the notches as they roll on by.