Finally acquired two of these beauties. These things are HUGE! I included a Westy incandescent bulb for comparasion. Only made between 1981-83 before being killed off by Phileeps.
T4 for "older" ones, but now there are more of them made with T3 tube.
BTW T6 was used for a particular model of tube, the F42T6, which is single pin, instant start. I think those were used in commercial fridges and freezers in grocery stores.
There are a number of T2 spiral lamps now. I guess CCFLs would be T1. Dave, I don't know how you found such a gem, with its original packaging, no less! I had not heard of these in 1982 - or I would have tried very hard to get one. In fact, I didn't hear of screw-in fluorescents at all until about 1987 when I heard of the PL lamp-adapter systems - which I couldn't get except through an electrical wholesaler, so I never got one.
@Alain, I got these through a trade with Chris (aka chrislights) who is a L-G member. We were surprised to find these! I have no definite memory of any Econ-Novas back in the day but I remember one Norelco SL*18 CFL with a prismatic diffuser on display in a window at a lighting store in Berkeley in '82-'83. Still it wasn't a big thing, professional applications such as schools were the first to use CFLs.
BTW T6 was used for a particular model of tube, the F42T6, which is single pin, instant start. I think those were used in commercial fridges and freezers in grocery stores.