In 4LO my GM transmission shifts immediately because the PCM reads vehicle speed from the transmission tailshaft instead of the transfer case. How do I fix 4LO shifting on a Land Cruiser LS swap?

Here is what the documentation says. Each point links to its source; details depend on your exact computer, harness and transmission.

• In some 4x4 transmissions the output speed sensor may be missing or nonfunctional because the tone ring is absent; the Quick 1 manual says to use a transfer-case speed sensor instead or install a 40-pulse tone ring. (US Shift)
• Some 4WD 4L80Es lack the output tone ring; in those applications the Quick 4 can use the transfer-case-mounted speed sensor instead, and the manual says to inspect through the sensor opening when tone-ring presence is uncertain. (US Shift)

Confirm against the instructions for your exact parts before wiring. More: Transmission control in our tuning guide.