dd heres an option for you. tak the housing you have, and go to home depot. go to the isle with all the pvc pipefittings. i found one that fits just right over the end of the ehiem 1250 that i have, i had cracked it just like you. i applied a little glue, and 2 bucks in fittings(even managed to get it reduced to 1/2 npt on the end
) a little glue and i was all set!
outta be cheaper/faster than getting a replacement. also for the ones like the rio where the input is not threaded this option would allow you to take it(with bushings) to any size you wanted and have it be effectively one piece.