Friend of mine and I are swapping engines in a 1999 S-10 blazer with a 4.3 liter motor. Now the effort is not a problem we both have a lot of experience doing this kind of work. The problem we are having is with information. The dealers don't seem to know anything and the salvage yards we are talking to are not always correct in what they have to say. What I am trying to find out is will an engine out of a 2003 Blazer work in a 1999 Blazer?

 

its not a drop in and go swap. Yea,itll work. but you may have a few sensors,which are different. You can always make the old ones work though.