This is by memory, but no. I believe the FL-820S is metric, like a M22 thread vs the 3/4"x16 of the FL-1A. A short version of the FL-1A would be a cross from the Fram PH16 used on a number of Chrysler products. (excuse the Fram number, I have most of those memorized.
The FL-820S is used on the mod motors.