Freightliner chassis ?
If so give the free help line a call with your chassis serial number .
If they didn't add any belts, or can't provide the diagram, then get your engine serial number from them , or off your engine , and call Cummins Care
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.