Just had a look at the aftermarket pipe and it's actually about 4" longer than the OEM one so might fit.
As I said, it just needs the flange welded on, it's there for it.
It's a 2.5" pipe than was designed to slide into a 3" pipe, hence why the flange needs to be welded on it.
I know it's not ideal but that option is there for you if you're stuck.