To find it, you need to:
1. Consult your owner's manual: This is the best resource. It will have a diagram showing the location of all relays and fuses.
2. Check the underhood fuse block: This is a common location for the fuel pump relay. Look for a diagram on the fuse block cover itself. The relay might be labeled "FUEL PUMP" or have a symbol that resembles a fuel pump.
3. Check the interior fuse panel (under the dash): If it's not under the hood, it's likely here. Again, look for a diagram on the fuse panel cover.
4. Use a wiring diagram: If you can't find it visually, a wiring diagram specific to your 1996 Chevy S-10 Vortec V6 will show the relay's location and circuit. You can find these online (often for a fee) through auto parts stores or repair manuals.
Without your specific truck's documentation, it's impossible to give a precise location. The visual identification in either fuse box will be your best bet.