D/G are found on pedals intended for 9/16 threading--they still show up like that occasionally (not talking about Maillard, like @
juvela likely is, btw).
1 million expert opinions are worth exactly 1 (or 2) thread gauges:
https://www.amazon.com/Grip-Thread-P.../dp/B004ROIU2A . It may seem like overkill for your pedal problem, but once you have one, you'll find yourself using it quite a bit.