Economical Discovery Series hydraulic excavators, designed to deliver ?more dig for the dollar,? are now available in two-wheel-drive and four wheel drive models. Developed by Gradall Industries in collaboration with Freightliner, Discovery Series D 152 and D 154 models are budget-priced and designed for excavating and maintenance work frequently performed by governments and specialty contractors.The D 152 with two-wheel-drive and the D 154 with four-wheel-drive meet specific travel and repositioning needs, operating on pavement, dirt, sand, mud or snow. On job sites, the machines can be repositioned from the upper structure operator cab, travelling at speeds up to 7 mph. Travelling to jobs or back to the equipment yard, Discovery Series excavators can be driven at highway speeds.