Abstract: An automatic transmission test apparatus includes an elongated main frame having a pair of inertia wheels supported at opposite ends of the frame for rotation about a longitudinal axis. An upstanding headstock frame on the main frame between the inertia wheels, supports an automotive engine and an automatic transmission in driven relation with the engine. The engine and transmission are so supported that their position can be vertically, transversely and rotationally adjusted for aligning the transmission outputs with the longitudinal axis of rotation of the inertia wheels. A jack shaft runs the length of the main frame for disengageably timing the inertia wheels for rotation in unison. Transmission fluid is stored within the main frame and pumped to a transmission through a dual filter system for reuse of the fluid. Brakes associated with the inertia wheels are operable by either of dual pedals provided on opposite sides of the main frame for convenient testing by an operator situated on either side.