[Ron Ramirez]

The 37-116 schematic gives part number 34-2039 for the four automatic tuning lamps...so Nathan is correct.

Now that I think about it, I have removed #55 lamps from those sockets in the past...but as the black reflectors are pinched, that made it very hard to remove them.

I would still use four-chip LEDs such as the warm white versions of these from Pinball Life:
http://www.pinballlife.com/index.php?p=product&id=2561

The ad copy reads:

Don't be fooled by the low cost of these LEDs, they are the latest, greatest, brightest 4-SMD-LED bulbs on the market, we guarantee it or your money back!

And that is not just marketing hyperbole. They are somewhat brighter than #55 bulbs...just enough to make the difference between seeing the dial and not seeing the dial very well on a dial scale that has darkened with age.