Cum chow bubba has nothing like this large fill petcock, if you're sick of cheap Chinese petcocks that are supposed to fit but don't and you were ripped off by some Chinese seller (aka Cum Chow Bubba) then look no further. I'm an honest person and know what fits.  I have been in the motorcycle business for over 30 years.This is a hand made custom fitted adapter plate that I personally make in my shop and a very nice aftermarket petcock,bolts,gaskets.  The combination fits the GT250,GT380,GT500,GT550,GT750.  Concerning years of fitment, if yours bolts on and doesn't thread on then this will fit your bike,  There is only ONE hose barb on this petcock, you will be plugging your vacuum line with a bolt or screw since it will not be used any longer.  The petcock is a fairly large unit with ON, OFF and RESERVE, the hose barb which supplies the fuel is 8mm (a little larger than 5/16") and faces downward at the rear, the length from base of adapter to the bottom of petcock is 2 1/2" the width of adapter 2 1/2"  You will receive everything in the picture, two bolts, two bolt gaskets, gasket between the tank and plate, adapter plate, o ring for the petcock and the actual petcock with sediment bowl.  This petcock will supply tons of fuel, kind of like a turbo petcock! The adapter plate is hand made, it is  not cnc made.  This unit as a whole is not available anywhere else in the world,  I ship from the mid west in the USA, my  ebay address is NOT in California but then ship items from China and I don't speak Chinese, I speak English so we can communicate.  Please read my feedback concerning quick shipping and quality products.  Check out my "me" page and notice I am a fellow rider.   Each one of my petcocks have been custom fitted in the USA to fit the listed motorcycle.  This is a manual activated petcock which eliminates the vacuum petcock that most models are equipped with from the factory.  The stock vacuum  petcocks are a bit of a mystery to many owners. They have no off position rather just on-reserve and prime. Instead they have a vacuum operated diaphragm that opens the fuel flow via a pulse hose from the carburetor when the engine is running. When the engine is shut off, the fuel flow is shut off. At least that is the way it is supposed to work anyway and most times it does. The problem is that as they get older, the diaphragms wear out and then the petcock doesn't allow fuel to flow or doesn't shut off anymore. In the first case, the engine can starve for fuel and in the second case the carb and engine crankcase will often become flooded when sitting causing starting difficulties.  Eliminate that junk high priced OEM petcock with this nice aftermarket unit with ON OFF RES.  No more headaches with the diaphram OEM unit!  Free first class shipping to the USA delivery confirmation included with Paypal payment, shipping to Hawaii, Alaska, Canada and worldwide will be extra, you have the right to pay me anyway you prefer.  Please do not use silicone on any gasoline item, silicone mixes with gasoline and just makes a mess!