As I presume you have access to machining have you considered using the to of a P/N rocker knob, if this is not viable for you at least one of the usual suppliers can help. Roger Cadogan
Richard. I think that Bryan Ditchman had a small batch made a few years ago - likely to be for P or N. I don't know whether he has any left but it could well be worth giving him a ring on 0118 932 6346.
One of the 4 spurs on the pattern was damaged at the foundry last time we did a run and just need to find the time to repair it. Running flat out on other work at the moment sadly
Is this any use? I think I got it from Rich Hardy to be fitted to the J2 sump but there wasn’t room for it with the assorted pipework I have so I ended up using the original dip stick cut to suit. The actual measuring part is 3 1/4” long. Yours for a tenner plus postage if you want it.