Peterbilt Motors Co. at the 2014 Mid America Trucking Show

One of Peterbilt's "75th anniversary" tractors; painted in the same color scheme decorating a 1939-era model being displayed in the OEM's Mid America booth.

A Model 579 sleeper tractor equipped with a Paccar MX-13 455 hp engine and Fuller Advantage 10-speed automated manual transmission.

A "square nosed" Model 389 equipped with an MX-13 500 hp engine mated to a Fuller 18-speed manual.

A CNG-fired Model 579 equipped with a 400 hp Cummins ISX 12 G mated to a Fuller 10-speed manual.

Peterbilt's newly-refreshed cabover medium-duty model matches changes made to the K270 and K370 over at its brother company, Kenworth.

A Model 579 daycab tractor powered by a 455 hp MX-13 engine mated to a Fuller 10-speed manual.

A rough-and-ready Model 567 vocational truck.

The Model 567 in tractor configuration.

A "looks-brand-new" 1939 Model 334 equipped with a then-powerful 125 hp Cummins engine.

The interior of the 1939 Model 334 features oak wood panels.

A cab interior display at the Peterbilt booth.

A close up of the dashboard and gauge clusters offered by Peterbilt.