ORIGINAL: skoda450
Fox is still very much in business but they have not kept up with the technology. They do not offer any ABC or exotic combinations. Nor do they offer any four cycle engines. They do have a line of gasoline powered engines in addition to the older technology nitro powered engines. You can do much better for the same money with OS engnies.
The venerable Fox 35 Stunt engine (for control line) has been in continuous production for nearly 60 years. Yes, it's old technology with steel cylinder and iron piston (although various ABC and now ceramic piston/liner sets have been available).
Run a stock Fox 35 on RC fuel and you'll kill it. Need castor and lots of it. One of my favorite ever (and best flying) combos was a C/L Ringmaster with Fox 35. Nothing quite like the sound of a 35 stunt burbling along in it's throaty 4 cycle setting then changing to a 2 cycle when pulled into a maneuver. They call that the 4-2-4 break but you need suitable fuel, plug and prop to do it.
I've had a few RC engines. The 40-50 sized engines appear to be very robust and quite heavy. They produce pretty good power though... Their 15 BB engine is wonderful.
No one will offer you the level of customer support Fox does. I sent them the remains of a 35 stunt I drove straight into the asphalt and got a new replacement motor for 50% of the new motor price.