I've got the '98 300 Cummins ISC, yours should be the same just different fuel mapping. Very bulletproof engine, I know on mine it could be pumped up to 350hp by local Cummins shop. The same 8.3 was used many years.
I use the LF 9009 extended service oil filter by Fleetgaurd and it will take approx. 20-22 quarts of your favorite oil. I use Delo 400 15/40.
Fuel filters are FS 1242 primary, FS 1251 secondary. Also I use the WF 2075 water filter with 15DCA units for the cooling system. All of these filters are found at filterbarn.com with good prices and fast shipping.
Good Luck, Rick
1998 38' Dutch Star 3865