How can you tell what type of torsion bars you have, if all you have is the torsion bars and not the truck they came of off?

The part #'s on the bars I have are RUF R648B (F57A-FC) & LUF R648B (F57A-FC) can anybody tell me if these are F, B or #1 Torsion Bars?

 

1 code torsion bars:

F67Z-5B326-FB Driver side bar
F67Z-5B326-FA Pass side bar


B code torsion bars:

F57Z-5B327-A Driver side bar
F57Z-5B326-A Pass side bar


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You can also measure the bar diameter:

1 / 1.09"
B / 1.06"
F / 1.03"