That looks very similar to what I replaced in my truck.
In fact, the clutch master unit is P4977 and the cap is shown as P4982.
I'll have to have a look when I get home, but I seem to remember replacing the one in my MK3 as it was cheaper than buying a rebuild kit.
The local Repco looked up the old PBR part number and found they were now made by Protex.
If I still have the old one, you are welcome to the lid, if its not cracked or perished.
Greg.