Is there a significance in the bottom number of this relay?

[Th1s_0ld_Truck]

I have a 1999 Ford Ranger 3.0L XLT with a drain or short somewhere in the PCM circuit. I determined this by using a test light and pulling fuses. Once found, I pulled this relay from the PCM power port for testing but apparently there are A types and B types which determine the location of the terminals. It would help to know the difference when testing with a meter. There are two other FOAB 4B192-AA relays in the box, one for the starter and one for the blower motor, but the bottom number varies by a digit. Once labeled, I would like to know if I can swap the blower motor with the I have pulled to see if it solves the problem.

 

[4x4junkie]

To me it would seem the numbers on the bottom are just a date or production code (maybe they were made one week, one month, or one year apart if there's only a single-digit difference).
The "4B192-AA" seems like would the more important number here.

If the physical pin config is the same, it's likely the same electrically as well.

 

[SenorNoob]

Searching that is weird. I get standard square 40amp 5 pin relays and rectangular relays with the same part number visibly printed on them...