I've been into 24 valve Cummins ISB (5.9) and ISC (8.3) engines, though not in the front engine Blue Bird application. If there's anything installed crossing over the top of the engine you'll have to move that aside first, but once it's clear, the cover comes off and goes back on easily. It's just held by 5 bolts. You'd probably want to replace the bushing around each bolt as well as the gasket under the cover. Depending on your inclination for "while I'm in the area, I might as well...." you might consider checking valve clearances while you're in there.
Do you have a free engine owner's account on Cummins QuickServe Online
? You just need your engine serial number to get started. They have parts diagrams available there with part numbers for basically everything on the engine. These come in handy particularly if you want to search for aftermarket parts (www.finditparts.com
for example). Being a 24 valve 5.9 you have lots of options for getting those parts -- a Cummins distributor, a Dodge truck dealer, pretty much any auto parts store, etc. Of course for most of these sources you'll be more likely to find the parts in the application guide for 1998-2002 (?) Ram 2500/3500..
If you do want to adjust the valve clearances then also look in QSOL for the instructions/specs for that. And look for the "engine barring tool." It's a little sprocket tool that engages with the ring gear around the flex plate -- the same teeth the starter motor engages. This tool costs something like $30 from Cummins, but it makes it SO easy to rotate the ISB/ISC engines by hand.