i changed an newer 4.3 with older 4.3 how do i get around crank sensor toget it to fire everything else matches and was swapped out correctley It came out of a 1994 blazer and i put it in a 1996 blazer

 

Need to get specific here... What years are involved; your truck and the motor you installed?

I'm not sure if you meant to post this in the Builds section, but I will move it to the appropriate tech section once we know what it is you are driving.