The Guy Big J6 was a 6-wheel chassis available as a 20-22 ton or a 32 ton vehicle, with  a wheelbase of 11 feet, 14 ft. 9 inches, 15 ft. 9½ inches or 16 ft. 10 inches.

The chassis was fitted with a 6-speed gearbox, could handle gradients of up to 1 in 3½, and was ideal for towing a trailer (32 tons).

The overall length of the chassis was 21 ft. 4 inches, with an overall width of 7 ft. 10 inches. The turning circle was about 48 feet.

The chassis was used for a wide range of lorries, tippers, tankers and concrete mixers.

The Big J6 was fitted with a V6 diesel which produced 170 bhp at 2600rpm with maximum torque of 370 lbs ft at 1700 rpm or an AV 505 (right hand only) which produced 170 bhp at 2400 rpm, or the AV,471 (right hand only) which produced 150bhp at 2400rpm. The Big J6 was fitted with a single plate clutch with cushioned drive.

The gearbox was a 5-speed constant mesh unit. A 6-speed constant mesh gearbox with under drive splitter was available on the double drive V6 model.

The suspension consisted of underslung semi-elliptic springs with balance beam carried on oil bath lubricated plain bush, fully protected from ingress of dirt at the rear. Front springs were 54" long and 4" wide. Telescopic shock absorbers were fitted on the front axle only.

A 24 volt electrical system was fitted with a 35 amp alternator fitted as standard. The fuel tank could hold 46 gallons.

Community content is available under CC-BY-SA unless otherwise noted.