The computer in a factory A518 (pre-94 auto OD) truck could run the OD, but not the lock-up. The transmission has one power wire and 2 grounds, the computer switches on the ground side of the circuit. You would need a stand-alone controller, the pressure switches, or a switch inside to manually engage the lock-up. On a factory manual-trans truck, or 3-speed equipped truck, you would need some way to control both.
There are stand-alone controllers that only require tach and TPS. But the pressure switches are a lot cheaper and accomplish the same thing.
You can make the Allison 1000 work behind another engine, the trick is to use one out of a medium-duty application. Since they had the Duramax or a Cat engine available in it, it picked up tach off an internal sensor instead of the engine computer.