I just now picked up a 1998 4.3L with 33,000 miles from a wrecking yard for $400.
As I was looking it over, we pulled the valve covers and found that it had roller rockers.
Did all these motors come with roller rockers. I can't remember exactly, but I want to say my old motor (1996 4.3) didn't have roller rockers. Maybe I'm wrong. When I get back to the shop, I will check, but just seeing what everyone else thought.

 

It turns out the motor is a 2000, I was looking at two motors at the wrecking yard (1998 & 2000) and got it mixed up. Had to look at the receipt. It turns out that this motor has 25,000 miles. So anyway, in 2000, Chevrolet put roller rockers and roller timing. This motor came out of a truck so it has 200 hp and 260 tq, so ten on each side is pretty good. Checked everything out and all the wiring works out perfectly, only had to change out the motor mounts. Just a little info to end the thread.