Help Identifying gas tank size

I need to know how to identify the size of the gas tank in my 69 XR-7. I replaced the tank about 10+ years ago with one I purchased from Mustangs Unlimited. I believe it is 20 gallons but want to be sure because I’ll be installing a Holley OE Style EFI Fuel Tank Module which comes with 3 fuel gauge floats.

It should be 20 gallons, but the 16 gallon and the 22 gallon will also drop in. If you didn’t have to modify the filler neck I would say it is the 20 gallon.

I assumed it was the 20 gallon tank but wanted to confirm. I didn’t have to modify the filler neck when the tank was installed. Thank you Bill.

How tall is the tank above the mounting flange?

I compared the tank to the one in my Eliminator and they appear to be the same. I firmly believe the Eliminator’s fuel tank is original. Was at a local cruise in Saturday and a friend with a 68 Cougar had installed the 22 gallon tank in his car. It is noticeably taller inside the trunk of his car compared to mine. I feel confident my car has the 20 gallon replacement fuel tank.