rpo codes np1 and np8

anybody know what the difference between these 2 rpo codes is? i am going to buy a driveshaft at the junkyard and the guy asked me whether i need code np1 or np8, my truck has np8 but anyone know what the difference is because np1 is more available than np8, there seem to be a lot more np1's. could i use one of those? my truck is a 2000 blazer lt 4x4. thanks

Np1 Transfer Case , "electric Shift Cont, Two Speed"
Np8 Transfer Case , "active, Two Speed, Push Button Control"

Thinking about it, it's probably the distance between the tailshaft on the transfer case and the rear diff. that makes the difference. (though i could be wrong)

ahh i see, cuz its weird i bought a driveshaft today and it was for an np8 which is my truck but it didnt fit (the driveshaft they gave me was from a 2002, could that be why?), maybe i should try np1 now??

What part didn't fit? Too long? what?

driveshaft i got from the j/y was too short, was the one from the 2002 np8