HELP! my mk2 granny estate rear suspention arm mounts are rotten!

hi there everyone,
im new to the forum and wa just wondering i any of you guys could help me out,
ive just baught an A reg mk2 granada estate 2.8i ghia X,

its a little beauty apart from the rear suspention arm mountings are rotten both sides,
im sure you guys will know where i mean as ive had a cupple of granadas before and this area has been repaired before,
to explain it a bit better its just under the end of the rear part of the sill were the suspention arm bolts up, neer the rear jacking point,

what im wanting to know is can i buy this part as a whole so i can just cut it out and seam weld the new part in? and if so where can i get it from?

thanks in advance everyone for your help/advice,
jamie