A 1R5 can also be used as a substitute for a 1L6 if the circuit has the proper resistor on one of the grids…I can dig through my info and sent it to you later today…but the 1R5 will not work above about 10MHZ…or very limited performance above 10MHz compared to the 1L6.
If I come across an Electro model of battery eliminator you can usually gut it and rebuild it with new parts ( since the original designs used either a vacuum tube rectifier or selenium rectifier ) and still use the sockets that are on the blue metal case. The AC transformer is usually still ok to re-use.
I can send you more info on that later today as well. I do not have any of that info on me right now…
PH