Verifone Tranz 330: multiple versions?

Are there multiple versions of the Verifone Tranz 330? I'm thinking of
getting one used - the bank is telling me to get the one with "more
memory". I looked up the specs - it has a Z80 processor, so I doubt it
could support more than specified 64K memory. I saw one website
(http://tafoyaterminals.zoovy.com/product/60) where they were selling
it with 128K memory. Are there any other possible features by which
different 330's differ? Any other compatibility issues?

Thanks.