That's good info, thanks.I tried to make one with a 40mm thermometer tube in a couple of different carbed pass through adapters and some heater carts from my collection but it wasn't very good. I think the elements I used were underpowered and the centre of the heat was in the wrong place for a GS
After some digging, I think this piece could be like the old one Popular glass used to sell. I asked the seller for measurements, let's see what they tell me.