I am planning an engine swap in my '90 K5. I had plans to do a BBC or maybe a 400 SBC. However, a guy told me yesterday that you cannot put an older block in my truck b/c the older blocks do not have the "crank sensor" (????) that tells the computer when to fire. I have never heard of this. I know tons of people have put 406 SBC's in trucks but I'm not sure if it has been done in the computer controlled models or not. Anyone got any knowledge of this?