Mack B-61 truck, Bridgetown Show, November 2007.

Engine: Six cylinder O.H.V. Mack diesel Bore 5", stroke 6" 707 CID (11.6 litre)
Transmission: Twenty speed Quadruplex gearbox (twin gear sticks). Dual reduction spiral bevel and helical gear set differential. Not actually 20 speeds due to gear replication - it has 18 speeds
Brakes: Air operated foot brake, Spring emergency brake and transmission parking brake.

Specifications from http://www.sydneybusmuseum.com/exhibs/061.htm . Thanks to Joe Hupp for providing theinformation and link.