I have replaced the fuel pump on my 1955 f-250 at least 3 times, maybe 4. The pump will work great when brand new, then it will start hard and finally fail completely. I doubt I have put more than 500 to 600 miles on any of them. I run 91 octane fuel which does not contain ethanonl (the gas pump does not have an ethanol disclaimer on it so I assume it is ethanol free). I have used fuel pumps with the fuel filter built in and ones without. I use the original fuel filter with the glass bowl and pleated filter inside when the pump does not have the filter built in. I believe this should eliminate any possibility of contaminants from the tank causing the failure. Has anyone else experienced this kind of trouble? Are aftermarket pumps that poorly made or am I overlooking something?

Thank you.