What year 4.3?
The "W" motor from the factory was rated 210hp net with a MFI set up and stock exhaust.
Cams, rods, cranks, and pistons were differnt from the "Z" motor and had the balance shaft because of the lightening of the rotating assembly.
The "W" had a better cam in it as well which helped achieve the 210 mark where the older 4.3's were only rated at 155 and 170hp net.