Jordan wrote:

Things are sometimes made that way. My MZ motorcycle for example had an
iron brake disc, but the centre of it is aluminium alloy - must be cast in.

Thanks. Looks like I am out of lack.

Here's a blow up from a DB200 parts list. It shows the stem as a

Actually I mislead you by the subj - mine is SL - with grooved pin
and w/o hole. Looking on the pictures I got an idea that this part
was common for both SL and DB.

separate part, and the method of holding it with a pin in a groove.
Note that the SL has a different method of clamping the headstock/stem
assembly to the bed, but it's likely the DB method is the same as on the
SL, as regards the stem to headstock question. Worth checking?

I checked. It does not have any clamping pin. And looking at the
entry point at the bottom and all this webbing around it - there is
no space for any pins. Even thread is very questionable - no any
traces of threading on the visible part of the stem as well as no
traces of machining around the entry point in the casting. I think
that suggested groove/fin and then molding as one piece is the case.

Thanks,
Arcady