[PeteVS]

Per my understanding, the '32-'48 and later pickup gear sets are:

16/28- Standard passenger gears.
15/29- "Pickup" gears with a lower speed first and second.
18/26- Zephyr gears with a higher speed first and second intended for a car with a high ratio rear end and over drive.
19/25- Also Zephyr gears, same application, slightly different ratios.