i]Is it true the grande was a US only model for 78-82?[/i]
under the vespa name, yes. the bike is actually a gilera CBA (note the down tube sticker on the attached bike), and they were badged as such for sale in europe. piaggio bought gilera in 1969.
they did this for name recognition, i believe. gileras were never widely distributed here in the USA, whereas vespa scooters were.
also of note, the mopeds were only refered to as "vespas" in the USA, and i'm not 100% certain, but it may have only been 1978 and later. they were badged as "piaggios" in europe.