DIY walkthrough: In Photo 2a I’ve replaced the Strat’s 5-way pickup selector with a Tele-style 3-way. I’ve threaded a wire through the two leftmost lugs of the selector’s spring side and the two rightmost lugs on the opposite side. Additionally, I’ve connected the bridge and neck pickups as shown in Diagram 2.
In Photo 2b I’ve added all the ground connections. The three pickup ground wires, output ground, and bridge ground are all soldered to the rear of the volume pot, with additional wires grounding the blend and tone pots. (All pots must be grounded in this circuit. It doesn’t matter where they connect physically, so long as they connect electronically.)
You must connect both the volume and blend control outputs to the output jack. In Photo 2c I’ve removed the jack plate to install a second wire that will connect to lug 2 of the blend pot. (Alternately, you could add a Y-joint inside the main control cavity, reinforcing the connection with heat-shrink tubing.)
Photo 2d shows the volume pot connections. One output jack wire connects to lug 2, while the pickup selector output (the rightmost lug on the non-spring side, as viewed in this orientation) connects to lug 3. Lug 1 is bent and soldered to the side of the pot for a ground connection, per usual.
The blend control wiring appears in Photo 2e. The hot wire from the middle pickup connects to lug 3, bypassing the tone and volume controls. The second output jack wire connects to lug 2.
Photo 2f shows the tone pot wiring. Lug 3 connects to the volume pot’s lug 3. Solder one end of the tone-cut capacitor to lug 2, and the other to the back of the pot, grounding it. I’ve used a .022 µF (223), a standard value, though you can step up to .033 µF (333) or .047 µF (473) for a stronger effect—the larger the cap, the greater the treble cut. If you like the sound of your current tone cap, just reuse it here. And that’s it!
Bonus bridge pickup tip: Like many Strat users, I have a love/hate relationship with the traditional bridge pickup. It works great when you want a clear, piercing sound, but tends to be short on mass. Some players remedy this by installing humbuckers or other higher-output pickups in the bridge position. But instead of trying to coax Gibson tones from a Strat bridge pickup, I prefer a Tele-style bridge pickup sized for Strats, such as the excellent Seymour Duncan Twang Banger. With its Tele-style metallic base plate, it provides tough, edgy tones with more mass than traditional Strat pickups—without relinquishing that fine Fender sizzle.