Okay so life finally got out of way enough to get these much desired photos up. BTW the propane tank conversion shown above does not work as the pressure is double regulated and severely lowers your BTU's on the grill. I did that first and the flame is almost non existent.
I am sorry that I cannot confirm the thread size, but that is easy enough to do. First buy your hose with 1/4 NPT fitting for gas on the end and then a male threaded end on the other. Don't go over 12ft here as the propane flow will be too low. Once you have the hose take it and the regulator to the HW store for fittings. You will need a union first out of the gate and that is what you see flush with the red casing. From there you need to build out and reduce as you go to fit your hose fitting threads. There must be minimum of 1/2" between the union and your new hose in order for the gas to flow as there is a problem with the two hoses meeting up on the pipe right out of the grill if memory serves me correct. It's been 4 years since I did this mod.
Sorry it took so long.