Where is the Slave Cylinder on a Chevy S-10?

The slave cylinder on a Chevy S-10 is located on the transmission, specifically at the connection point between the transmission and the clutch fork. It's not readily visible without some disassembly; you'll need to get under the vehicle and look near the bellhousing area of the transmission. The exact position will vary slightly depending on the year and transmission type (manual, of course, since automatics don't have a clutch).