Orifice Tube Location

You did not say what year, but, here goes anyway.

It should be located on the evaporator inlet tube. It should be in at least a 2-3 in section of tube. If you have both hoses disconnected, you should be able to see it.
 
Actually you wont be able to see it if it is a factory line. It will be in the liquid line coming from the condensor. It will be the line that has some foam on it. The orifice tube is in this line. It is crimped in and not removable unless you cut it out and replace it with a inline universal oriface tube. I would just buy a new liquid line.
 
Does it matter which end of the liquid line it goes in.
I have removed the old liquid line, cut it apart every couple
inches, and there is not one in it. The new orifice will not
go in the evaporator end, but will go in the condenser end of
the liquid line.