Got some old R types somewhere (much to the spouses dismay), got both Oldham and Exide, the filler plug on the Oldham was about 1" dia, with two tool holes in it, the Exide a little larger with 3.
The red model was the original type T iirc, the first Oldham to have open filler holes and belt hoops moulded on rather than the seperate metal clip.
If I can dig them out sometime, I'll take a few piccies, didn't realise they were curiosities.
Got some old metal NiFe's somewhere as well, a few two cell ones I got from the fire service, never seen those anywhere else before.
Always remember, nature is in charge, get it wrong and it is you who suffers!.