So I just looked up the FEL-PRO OS 13260 T Oil Pan Gasket to order and the guy there said that is only for the 289/302 engines, not the 351 😔First of all, it's hilarious that CantMeasure would point at any other product and say "that will make it leak". They have leaking down to a science themselves. lol
I used the 1 piece gasket and mine is now leak free (I have the Canton Road Race pan). You need to use the gasket for the older cars (Fel-Pro OS 13260).
You have to be sure to silicone the hoops at both ends (despite the instructions saying not to) and the corners. But you have to do that with any gasket when the pans fit as badly as the Canton ones do. This is what Jim at Ford Strokers advised me to do.