You could go for the one I posted in
this thread
It's 10 3/4 inches high, by 5 5/8 in. wide and 2 inches thick. The inlet is 3/4 and the outlet is 5/8. The dimensions might not be exact, as the tanks on those things are outside of those measurements.
Drop by your local auto part store, and ask to see it, so that you can measure it.
Let us know!