The only difference that I can see between the 2240 and 2240Z is in the lower fitting (see photos). The 2240Z seems to come to more of a point. I looked at your guide and wasn't sure which channel balance to order series 351 or series 390) or if I needed a special order since neither of the bottom fittings seem to be exactly identical. Thanks for the help.
PS The 2240Z is in the foreground of the photos and the 2240 is in the background.
