well if you're really old school this is the beast of nurgle
http://toyarmies.com/wiki/index.php/%D0%A4%D0%B0%D0%B9%D0%BB
oC-4-BeastNurgle.jpg
more recent (and available in 2 versions with slightly different heads) was this
http://toyarmies.com/wiki/index.php/%D0%A4%D0%B0%D0%B9%D0%BB
oC-4-BeastNurgle.jpg
but you look to have the most recent version there (which got moved to finecast),
and I've not been able to track down any reference to there being different versions of this (but only moans about how people could field units of identical minis)
so are you certain there were two versions of this one ?
(the only reference to A/B I've found is this US seller
http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050430.m570.l1313.TR11.TRC1.A0.H0.Xbeast+of+nurgle&_nkw=beast+of+nurgle&_sacat=0 who has 3 which he's labled A, B and C but I'm sure that's just to show there are three separate lots on offer)