Alloy Head No.

[cus]

G'day All,
On the alloy head of my '63 s/r, it  has an additional number stamped next to the manifold 52A17HL (numbers stamped in), as well as the raised
number under the manifold, which is the standard s/r head number. Does anyone know what this is for,

regards, Cus

[bonny]

i don't know what those numbers are for , but can guess assembly numbers ? mine has 47A15lG stamped in the same area .