both are and were efi, but i plan to take the ecm and everything else i am more concerned with the drive shaft length and the bolt pattern on my frame to fit the 2.8 motor mounts. i do plan on switching the engine trany and drive shaft. what was your concern with the EFI, oh, both are 87's just the s10 had a iron duke and the blazer has a 2.8 v6. again thanks. neuf62