For sale is a Caterpillar Parts Manual for GC15K (AT81C-00011-Up) GC18K (AT81C-00011-Up) GC20K (AT82C-00011-Up) GC25K (AT82C-00011-Up) GC30K (AT83C-00011-Up) Chassis and Mast - LP Gas. For use with 4G63 4G64 Engine Parts Manual. 98715-73000.