A500/A518 to Gen-III

The H series transmissions simply have a 3 wire connector to control OD and lockup. All you need are two switches, either manual toggles or a pair of vacuum / pressure switches (barometric) If you go to the "free manuals" thread there is/ was a russian site where you can download the ATSG transmission books

Free service manuals

Here

Коробки передач | Интернет-магазин запчастей для автоматических коробок переключения передач