You're describing your RV as
"1991 Ford Econoline 350 Tioga RV"
We need to know the Model Year of your Ford E350 Chassis. I looked up AutoZone and found a number of stores within a few miles of Zip 34653.
Chassis Year is really important because the Chassis is as often as not a Model Year OLDER than the "Coach Year."
We also need to know the Production Date of the Chassis. In that AZone lookup, there's a date of 5/22/90 that affects the model of pump.
Finally, How many Tanks and What Size(s) are they? If it's a two-tanker, which pump are you trying to change?
With more info I think we can locate the correct pump within a few miles and a couple days or less from you.
Also, don't forget about NAPA. They generally have experienced parts people. People who weren't asking "Do you want Fries with that?" last week.
Just visit any auto parts on an off day/off time. If it's tricky, you don't want the counter in a time crunch serving a backlog of Saturday DIY customers.
