* Different Transmissions: Thunderbirds used front-wheel-drive (FWD) transmissions, while a 1993 Ranger 4x4 uses a four-wheel-drive (4WD) transmission, which is completely different in design, size, and mounting. The bellhousing (where it connects to the engine) will be incompatible.
* Transfer Case: The Ranger 4x4 has a transfer case to distribute power to the front and rear axles. The Thunderbird has no such component.
* Output Shaft: The output shaft on a FWD transmission is oriented differently than a 4WD transmission's.
Even if you could somehow overcome the physical incompatibility, the electronic controls and computer interfaces would be totally different and wouldn't work together. You'd need a 4x4 transmission designed specifically for a 1993 Ford Ranger to make this work.
