RazBRZ, thanks again for the idea.
10-2-12 Ran to Wallyworld and picked up a Kidde Auto Fire Extinguisher. Same dimensions as yours. Ran $14.00
I made a mounting plate out of 3/16" aluminum. 5" x 4.25". Drilled and countersunk for the extinguisher mount and drilled for the armrest bolts. I ended up using some longer bolts that I had to mount the plate.
Here's a couple more pics showing the plate with the bracket attached and showing the unit assembled.
Ignore the slots on the side of the bracket. This was scrap material I had laying around. In this case, it's part of a 3U panel blank for a computer rack.
