These transmissions were staples in 20th-century pickup trucks and are now highly sought after for off-road Jeep conversions: Muncie SM420
: The first gear ratio is exceptionally high (often around 6.5:1 or 7.0:1), providing immense torque for starting heavy loads or crawling over obstacles. granny trannies
: Heavy-duty gearboxes frequently used in Ford and International Harvester trucks. New Process 435 (NP435) granny trannies