Flying Lawyer,
Cessna 421's :
* May be turbo-props (when modified); and,
* May have 6-7 seats and still be an "executive" aircraft.
A typical Cessna 421 interior has :
* two crew seats (or one crew seat and one pax seat if you like);
* a "single club" (four seats facing each other);
* a single side-facing seat opposite the entrance door (usually with a toilet underneath);
* and quite often there is a single forward facing seat right down the back on the left just aft of the entrance door.
This makes for a total of up to 8 seats. I have never seen or heard of a 421 with more than 8 seats, but have seen plenty with less than 8 seats.
For some pictures of typical Cessna 421 interiors take a look at :
http://www.aircraft.com/listings/for...D=1034269&nh=0
or at :
http://www.aircraft.com/listings/for...D=1031862&nh=0
Now, about the Cessna 421 turbine thing. You are correct in that all C421's were piston powered when they were built (Continental GTSIO-520).
But at least two C421 aftermarket re-engining programs were offered. Both resulted in turbo-prop Cessna 421s.
One program used PT6A engines, and you ended up with a poor-mans Cessna Conquest I. Pictures of genuine Cessna 425 Conquest I's can be seen at :
http://www.aircraft.com/listings/for...mdl=CONQUEST+I
I cant find any current pictures of a re-engined PT6A powered Cessna 421 as there dont seem to be any for sale at the moment. Please be assured that I have seen pictures of them in the past.
The other aftermarket re-engining program used Honeywell LTP101-600A turboprops. Dont ask me any details about these engines because I dont know any. Here's some details and pictures of a "Cessna 421C Riley Rocket" with the Honeywell engines :
http://www.aircraft.com/listings/for...D=1029714&nh=0
Flying Lawyer, I hope this helps. Keep up the good work.