clutch slipping, crank seal?

[Hecky]

as title, is this possible?
am i right in thinking the crank seal is behind the flywheel?
if so, would this being broke cause oil to get on the flywheel and clutch and therefore make the clutch slip?
i have noticed the engine oil level going down steadily over a period of time which makes me think this could be it
how big a job is it?
also which seal would it be?
this one www.106parts.com/s2/pa...&part=2514

or this one www.106parts.com/s2/pa...&part=2513

cheers in advance

[shakey1987]

yer defo if the crankseals gone the oil will jus end up on the clutch plate and will slip its tits off job ent that hard jus get box out and get flywheel off then jus press new seal in takes bout 10 minsafter u have the box and clutch out

[Hecky]

which seal is it though?