[Arran]

 From what I can recall most, if not all, of the non rear projection RCA TV sets from 1948-50 used a simplified and cheapened version of a 630 chassis, only retrofitting it to accept larger picture tubes as opposed to the 10BP4s that the 630s used. Unfortunately as the demand for TVs started to rise the build quality of RCA's TV sets also went down, it's not unusual to find sets with wiring errors and unsoldered tie points from what I read.
 Metal coned picture tubes were an RCA  development, I don't know how much cheaper they were to produce but on a larger screened tube that feature did reduce the weight. Unfortunately RCA also thought that using a metal cone was a good idea for their first production colour set, the CT-100, and more then half of those that still have the original tube have gone to air.
Regards
Arran