LOUISVILLE, KY -- Mack announced some updated to its Granite vocational model at the Mid-America Trucking Show Thursday.

The Granite gets new twin-steer packages, said Curtis Durwart, vocational segment manager. The twin-steer, common in Quebec because of its axle-weight law, now can be configured with the exhaust aftertreatment equipment mounted rearward, behind the second steer axle, or vertically, behind the cab.

Granites now also feature Body Link III wiring. Designed with extensive input from body builders, the electrical system provides an under-cab 29-pin connector, cab pass-through boot for a quick and reliable body hookup, and assignable in-cab switches.

First announced last week at ConExpo show in Las Vegas is a sleeper cab version of the Granite. With a 36-inch flat-top sleeper compartment equipped with a curtain, bunk restraint and a 30 by 80 inch mattress, the axle-forward Granite Sleeper allows drivers to get legal bunk time to meet hours-of-service requirements.

And a Granite Medium Heavy Duty (MHD) model uses a lightweight powertrain headed by a Cummins ISL9 diesel. The new Class 8 model is aimed at dump, "bridgemaster" mixer, and municipal customers who want to cut tare weight and don't need large-bore power, Dorwart said.