We may know some more at the end of the week... the basic 500 in all its forms is being produced at a fair rate mainly thanks to orders from Boein but lately the 900 has not been featuring.
It is likely that there will be a new Explorer at HAI this week but it will likely be an equipment change rather than growing something obvious like 2 tails or an extra row of seats.
The 900 was the original model but it did not comply with JAR27 so was sent back to the workshops for major mods so it could honour that first big order for ten police machines for PAS into the UK in 1994.
Mods mainly related to seperating the engines and fuel tanks but it was pretty major to actually acheive it and the Belgian Police are currently upgrading each of their 900s to 902 standard.