Don't know for sure but
try this as I'm a Plus 8 man but that level of general rust looks pretty advanced imho.
Loads of Roadster owners on here so someone will pop up in a minute.
My 23 year old car doesn't have a trace of it but had only covered 18,000 miles when I got it and now she is up to 37,000 miles used all year round by me for 8 years but never on salted roads.
So I'm thinking yours must be an all weather high miler.
![[Linked Image]](https://tm-img.com/images/2022/06/17/MBH0675_1.jpg)
Sorry, I didn't see this picture yesterday, and that part is identical. That outlet with the white cap is attached to a tube that goes to a little reservoir with Lockheed on it. I just assumed Lockheed had something to do with brakes. That red bit on the end must be a plug as another hose is screwed onto this end.
I've been under this morning treating the rust and it isn't as bad as what the photo suggests once a good scrub and painting of rust converter. It did give me a chance to have a look around in detail when under and have discovered a slight leak from the gearbox drain plug. Bit more ptfe tape me thinks.
I also found an electrical lead whilst looking at the gearbox that wasn't attached to anything. Photo to follow.