Chrysler and General Motors are the latest truck makers to add to the natural-gas fleet: Both are unveiling plans to manufacture pickup trucks that run on the alternative fuel at this week’s Work Truck Show in Indianapolis.

The Chicago Sun-Times reported that by the end of this year, General Motors will sell a Chevrolet Silverado and a GMC Sierra that will run on gasoline and natural gas, the company said Monday.

The “bi-fuel” vehicles will be built in Fort Wayne, Ind., and sent to GM’s Union City, Ind., plant to be retrofitted with compressed natural gas fuel tanks, GM said.

Chrysler is expected to announce Tuesday that a Ram truck to be built in Mexico will travel 255 miles on natural gas before automatically switching to an 8-gallon gas tank..

Ford Motor Co. has said it will expand the variety of kits it provides to convert an existing vehicle to run on natural gas to include the Ford 650 pickup later this year.

Honda has sold a natural gas-powered Civic for 14 years.