Hello leaky,
If you want piston tanks then I would strongly reccomend the Engel piston tanks, absolutely superb quality, sealed units too no poking out from the end of the hull just an inlet pipe to your tank, you can order direct from the manufacturer in Germany, and they will post direct to you, About a week when I order stuff, full spares back up etc, etc,. A salcon appears a bit dated these days, far more modern levelling devices are available from Engle, Subtech, Bruggen etc. as far as I am aware Mr Perrott gave up about 1998...a few probs I think !.
Check out the Engel web site at
www.engel-modellbau.de click the english version and your off, you can ring them up too and ask for Mr Gregor Engel....the managing director and owner who speaks perfect English and order with your card, all vat paid etc as its within Europe, and you pay in Euros not pounds so its all cheaper than you can get here...check out the prices on full sub kits, then do the same here for the same thing, you will weep.

Hope this is of use.