if you aren't happy with the dippy fire extinguishers you find at wal-mart
and k-mart, check the yellow pages for Fire Extinguishers or Fire Protection
& Supply Equipment. also check for a large truck supply (for 18-wheelers)
company ... they sell BIG (10-lb) extinguishers to go in the big trucks.

good luck.
joel
(i mounted mine in the little corner at the front of the sliding door,
right behind the passenger seat).