4.3L Power!

The 3.9 is worse actually. My Dad owned 3 S10 blazers, that's a fairly decent engine for the time, would take it over the 3.9 or the Ford 4.0 (either version)
My personal preference is the 3.9. Having owned/worked on them all, I feel like the reliability and performance was far greater than either 4.3 or 4.0.