I am not sure which engine is in your 1998 Chevrolet S10 so here is information on both the 4 and 6 cylinder engines. The 2.2L engine does not use a PCV valve. On the 6 cylinder engine the PCV valve is located in one of the valve covers.
You do not indicate if you have the 2,2 4 cyl or the 4.3 V6 Engine- However, here is the locations of each . On the 2.2-- 4 cyl. it is in the valve cover on the right side toward the front -- you will need to remove the resonator box from the top of the valve cover in order to access it . If you have the 4.3 V6 it is located in the drivers side valve cover just behind the oil fill tube as you face the vehicle standing directly in front of the vehicle .
To the 'visitor' who wrote: "yes the 1998 s-10 does have a Pcv valve. It's located on the back of the valve cover with a hose running up to the the box connected to the throttle body." ..... saying "the 1998 s-10" doesn't tell us anything of value because it could be 1 of 2 different engines, the 2.2L or the 4.3L, and from what i've seen others say, the 2.2 does not have a PCV valve but the 4.3 does. Now i've also seen others say that the 2.2L DOES have a PCV valve but that it's located on the front RHS (passenger side) of the cover. This i will explore. If you're taking about a 2.2 when you say "at the back of the valve cover with a hose running up to the box connected to the throttle body", then you're wrong. I took mine apart today and that silver cylindrical metal thing that looks like a PCV valve, is not. It's empty. Hollow. No guts. No valve. However, i also know that some people get back and front mixed around. Or maybe to be more fair, it's because it depends upon your definition of "back". To me "back" means closest to the rear of the engine, which is near the firewall. Be sure of what you write and also be specific. This is precisely a huge part of the problem with seeking info on the internet...too much crap to sift through. One never knows if they should trust and believe what they're reading!