VMaxF1

This one is a bit of a long shot, and I'm mostly looking forward to reading all the other excellent questions and responses (and thankyou so much for your time sharing your amazing experiences!), but here goes.

This picture is a U-2 cockpit, and neither I nor my friends can work out what the vertical tape-like instrument is on the far left of the display, with a bug(?) at 6 and a white ".35" readout.

An SR-71 seems like simultaneously the closest and furthest thing from a U-2 that exists, so I wondered if you might have any ideas!

Thankyou again for your time, and your service.

I could swear I read an article recently where it was mentioned that the Russians did exactly that (from ships off the coast of Florida, I think?), and there was some realigning of antennae or something required. I can't remember where I saw it now, maybe an article about JoAnn Morgan?