Cat D6D Welder Tractor S/N 4X09918 by cefar | Jun 11, 2013 | Welder Tractors and Tack Rigs - Rentals | 0 comments Monthly Rental Rate: $7,500 Caterpillar D6D Welder Tractor equipped with (4) Lincoln DC-400 Welders, Quincy 390 compressor, lead boom and outlets.