E 2040 This one is about 61/2 inches long and will fit the air-maze end caps. The shorter filter will also work but I prefer the larger one. You might consider buying the cleaning kit also.
I have used this size air filter for several years and have not noticed any adverse effects in performance.
I mounted mine below and ahead of the carburetor and put a weep hole in the bottom of the connecting pipe at the low spot. This locates it down in the engine pan area towards the front. It can also be mounted behind and above the carb, This method puts it closer to exhaust manifold, gas line, and sediment bulb. If mounted this way, I would still put in a small weep hole in the low spot of the connecting pipe.