[Milsurplus] BC-221 Questions

[J Forster]

I recently acquired a rather nice BC-221-AK and have a few of questions:

1.  What was the usage of the metal v. wooden cases? The other two -AK
units I have are battery powered and are in wooden cases, but I'm almost
certain I've seen metal case battery units too.

2.  Did the metal case units have a telescoping antenna? Mine has a
double "D" hole on top toward the rear and left side that looks like it
might have been intended for an antenna mount. My wood cased units have
no such hole.

3.  The newest unit has what appears to be an original RA-133-B AC PS
installed. What I find a bit odd is the line cord is not attached and
does not hang out the back as with many WW II instruments. Instead,
there is a recessed connector on the left side, similar to those used on
the older (pre IEC) HP instruments. It's very well done, if it was a
later mod, in that the the edges of the clearance hole are also black.
The front panel of the AC PS has two toggle switches and an engraved
plate warning that the rear door should be left open when operating the
unit.

Any input would be appreciated,
-John