[Jimski]

hello all,
while upgrading my G3 (M41)'s V2 gearbox I noticed that there is a threaded hole at the back of the spring guide for a big screw that hold a plastic part at the back outside of the gearbox.
Is that standard? i.e. will it be present on whatever upgrade spring guide I buy ?
I searched in google images but it's not clear.

thank you!