Will Toyota Tacoma upper control arms work on an FJ Cruiser or 4runner?

No, the Toyota Tacoma and Toyota FJ & 4Runners have different taper pins in the upper control arms. Toyota truck share the same ball joints and Toyota SUV’s share the same ball joint. A truck UCA can be converted to fit an SUV and vice-versa if the ball joint is converted to the appropriate application.

Toyota Trucks:

614550 - 05-UP TACO/07-UP TUNDRA/16-UP TITAN XD/19-UP GM 1500 DELTA JOINT KIT

Toyota SUV’s:

614551 - 07-UP FJ/03-UP 4RNR/08-UP LC 200 DELTA JOINT KIT