Got this fuel pump relay in a swap, but noticed the pin far right on its own wiggles from left-right..butim assured it does work.

Does anyone know what this pin is for, is it an earth or soemthing?

Also, My car is a series 1, but has a series 2 fuel pump relay holder, I got the car with a wire bridging the fuel pump to run constantly, as no relay was present...

Im not sure if its only the holder that has been changed, im assuming it was changed to accomodate a serie 2 fuel pump relay as they are easier to get a hold of....however ive got the series 1 relay as its more reliable than a series 2 effort and im told the wiring positions (if previously changed for an S2 relay) can be swapped back round in the S2 holder to refit the s1 relay....does anyone know which wire goes to which pin on the S1 relay? and what about this extra pin?

beside the pins on the relay I have the numbers:

30
31
87
15
1


And the one on the other side on its own is:

50

any help would be appreciated, would like to get it running on the S1 relay for friday when im insured to drive the car legally for the first timeever in 3yrs