Question on a A904 with photo

I am changing my trans fluid and filter.
I seen a locknut/bolt thingy in the photo, inside the transmission. Is this a reverse band adjustment?
I looked on the side of the transmission, and I don't see anything else. I thought there would be a forward band adjustment on the side, but its not there. I don't even know if I have to do this. Just guessing I may? Shifts fine. Does go into gear hard once in a while when going from park to reverse, or into drive. But shifts great, and smooth.
my car is a
1971 Valiant 225/A904