Changing oil seals...

Hello all, I'm going to spray an underseal/ protector on my Disco 300 TDI sometime this spring and change the clutch while I'm at it. One thing I've noticed is that there's sooooo much oil under there that I can hardly make out what's what, so while I've stripped off the exhaust, props, and gearbox (before I spray the underseal) I might as well clean up what's down there and replace as many seals as I can. Can anyone give me a "head's up" on what to watch out for and also what seals/gaskets I should change?

Cheers
Al

before you start changing seals give it a good cleaning get all the old oil and grease out then give it a good run on the road ( 1-5 miles) and then have a look at where the oil is leaking from then start changing whats bad .