I've spent a month contacting fire system manufacturers and searching the net looking for a mechanically operated, non-Halon fire bottle that is similarly sized to the OE Spa bottle our early VDs came with. The Spa bottle is 9" with handle, and fits nicely between the 10" spaced frame rails under your knees. The smallest I can now find is the Lifeline 2.25L bottle at 11.8", or the Lifeline 360 bottle at 10.8", but that requires a whole new system as the bottles are not compatible. There are electrical systems in the 8.5"-11.5" range, but I'd prefer mechanical, and the small ones are $1000+.
So I've now been looking to see if anyone would empty my Halon bottle and fill it with something SCCA approved, but no luck there either. Ideas???