Ryansf,
I'm afraid I don't know which aircraft has been operating MAN - MAH recently but knowing Monarch my guess would be that it's been a mixture of their 320's, whichever have been based at MAN at the time. They don't tend to assign a particular aircraft to a route.
Your best bet would be to try and get hold of someone from Swissport at MAN, preferbaly who works in Ops. They may be able to answer your question more accurately.
Sorry I couldn't be of any further assistance.
FlyZB