I had no idea these existed !!! https://www.scribd.com/document/331636208/GE-Lighting-Systems-Outdoor-Lighting-Designers-Guide-1972
 Catalog pages 24 & 25 .

Geez, that'd be painful to be under!

I’d imagine the TC-1000 was probably very unreliable due to the heat accumulation with this style of fixture.

 I'd assume it had some form of ventilation system in it . Besides the TC-400 was 34" tall by 28" wide and reccomended to be mounted at 18" and the TC-1000 was 48 1/2" tall by 39" wide and reccomended to be mounted at 25" . Plus , the TC-400R was designed to be used as a roadway streetlight . It'd be interesting to see photos of these installed somewhere .