My understanding was that the TEE (from Steve) replaced item A which is some type of damper meant to reduce vibration from discs being slightly out-of-true. Item B is (I believe) the proportioning valve and has the brake light switch. I had intended at some point to replace this with an adjustable Wilwood one like I have in the GT40 (in-cabin, no less).
If you can post a similar pic of your set-up, that would be great. Don't forget to rip out the carpet so we can see what really lies beneath!

Thanks!