Here's a neat old laser I recently found and just finished cleaning up. It's a 1968 Bausch & Lomb Model 41-17-50 He-Ne.
The plasma tube is missing but everything else is there. Wood structure looks like walnut to me, There are two pins on the back side of the central support that apparently held a spring to support the bottom of the plasma tube against the two adjusting screws above. Ignition coil!
I got the instruction manual with the laser. Here's the page showing the plasma tube, the only one I've seen without a reservoir tank! I guess they considered the "sidearm tube" adequate. The mirrors were apparently on the ends of the tube, which was held in position on both ends and pushed into alignment with the adjustment screws. This is the second laser I've come across that used tube bending to adjust the mirrors.