difference between c and j series 6.2?

[Thor]

I have a 6.2 out of a mid 80's blazer and putting it in my 89 K2500 pickup, how can I tell which I have j or c series, and what are the basic differences? Thanks

[gmctd]

C will gonna have EGR - J will not gonna...........less'n yer in Kalifornia, or the truck was bound for there, eh?