I don't actually want to run it, oddly enough, which is why any reasonably large 1.4 codebase will do.
There's no use of the more advanced 1.5 language constructs, but manually removing all the use of Generics for collections and inserting all the necessary casts as well as re-writing all the for loops would be way too much work to bother with.
I wasn't sure there'd be such a thing either, but the chap supervising my dissertation seemed to think there would be.