Try the link below. The Mission 773 is listed and has all the tech info on that cartridge...
http://www.cartridgedb.com/
http://www.cartridgedb.com/
info on mission 773 cartridge
i have an old rega p2 with a mission 774 pickup arm and i recently purchased a mission 773 cart. and installed it. i have it set at 2g tracking force and running it throught a unico phono set on mm. this sounds amazingly good for such an old cart. i can not find any specs. or history. help.