[Tigers] Radiator header tank question

[awtiger at cox.net]

Hey, guys:

I've messed with Tigers now since 1979 and yesterday I saw something that I've
never seen before.  I'm hoping that someone can enlighten me.  I have a spare
radiator header tank for a Tiger in my parts stash that was given to me by a
friend several years ago, along with a bunch of other spare Tiger bits.  I had
never really looked at it before, other than just a cursory glance.  However,
yesterday I unpacked the box that all of these parts were in and examined that
tank.  Just inside the radiator cap opening, there is a square-shaped "U"
piece of metal that hangs down.  On the flat surface of this piece, it says
"water level."  Of course, I understand the significance of the piece.  I am
puzzled, however, because it's the only Tiger radiator header tank that I've
ever seen that had such a water level indicator in it.  Niether my current
Mk1A nor the other three Tigers I've owned (all Mk1's) have had that piece
down in their tanks.  Are they supposed to have it?  Does anybody else have
this on their Tiger?

Thanks in advance,
Andy Walker
Edmond, OK
B382001600LRXFE
TAC #740