Crankshaft position sensor. Do I have to re learn?

[stryped]

I have a 1996 silverado with an intermitent problem. I bought a replacement crankshaft position sensor. I have two questions:

 

1: I read that there is a relearn procedure. If my understanding is correct, this is just to turn off a check engine code, right? Even with this code, the truck should drive fine? I dont want to replace it and be stranded.

 

2: The new sensor has two spacers and says to only use them to ensure the distance from the tip to the inside of the cover. (crank?) is a certain distance. It mentions a tool to use but every parts store I ask has no idea how to use it. I think as the front crank bearing wears the distance is reduced from the sensor to the crank and these spacers compensate for that. My truck has 347,000 on it so I am assuming they are needed but is there a way to acurately measure this?

 

I appreciate any help!