Does anyone know of a basic lift kit for a 2003 S-10 4x4? It is not the ZR-2. This vehicle is not a "pre-runner". It will only see light off-road action. The person who owns it just wants to be able to run a slightly larger tire.
The Rancho is next to impossible to find. It's part # RS6438 and Rancho hasn't listed it or mentioned it for quite some time. It's a 3" Front and 3 Rear kit and according to Rancho it's only designed to fit the 83-93 S-series 4wd vehicles. And it ain't cheap... the most current pricing I have for that kit shows it sold for around $1400 bucks.
The front suspension of the S-10 4x4 has not changed since its inception. Although the frame may have changed (where the replacement torsion bar x-member is located). But other than that, its the same old thing. The ZR2 even uses the same (to the naked eye) a-arms.
The problem you'll have with installing it on a newer than 93 model is if there are any problems along the way Rancho most likely won't want to be held responsible. Blazair is right though, the S-10 is the same throughout 83-present. The reason Rancho doesn't show more current information is because they have not physically installed the kit on a newer than 93' model.
The other problem with the Rancho kit - it has been discontinued. They are no longer producing this kit. Whatever they have left in current inventory is all there will ever be. The S-10 kit was a super slow mover for Rancho and they dropped it from production a while ago. When the current inventory of parts is gone, it will be next to impossible to get warranty replacement items should anything go wrong.