The Altezza diff that came with my halfcut had what appeared to be a G series flange which was 60mm square, this is a different pattern to all other F series diffs I've used (which are 55mm square if I recall)

So no, your Altezza tailshaft probably won't bolt up to the YR22 diff - but seriously this is the least of your worries as the tailshaft will be completely different lengths on both pieces and you'll need to get a new one fabbed up anyway.

You'll need to either get a 60mm square flange and put it on your YR22 diff ( diff rebuild time ) or the much easier option of finding a tailshaft with a flange that matches your YR22, and hand that to whoever is going to be making your new tailshaft.