Hi guys

XJS 3.6 auto

I think ( I know ) I've got a leak of transmission fluid from around the transmission bits and bobs.

Looking underneath I see a box shaped item which is probably a sump as the filler pipe leads into this. At the side of that there is drum shaped thing ( with a little rubber thingy stuck in it )and I seem to be loosing fluid from around there, the drum.

The questions are ???
1) What's the drum shaped thing with a rubber thingy in it?
2) How easy is it to fix the leaks with the whole unit in situ.
3) Would the lack of fluid prevent the car from going into gear ? I'm presuming yes !

I can add pics if needed.

Thank you

Carl