The early stunt Fox 35s used an Austin Craft universal needle valve assembly. There are pics on Bill Mohrbacher's Fox 35 ID thread on Stuka Stunt - http://www.clstunt.com/htdocs/dc/dcboard.php?az=show_topic&forum=103&topic_id=323889
I want to say that some of the 1952 engines used the Austin Craft assembly too.
The entire Austin Craft assembly can be replaced with the entire Fox unit, but none of the individual parts are compatible with the other. Ironically the Austin Craft needlevalve is much better for fine adjustment than the Fox flat sided needlevalve. Something of a moot point as Austin Craft is all but extinct and they're kind of hard to come by.
Austin Craft, Kap Pak, and Perfect all sold universal needlevalves that are remarkably similar, but the parts generally won't interchange as the spraybar threads are usually different. Some of the universal needlevalves are really terrible quality. They like to vibrate loose, or the spraybar breaks in two at the hole in the middle, or the needle leaks or is so loose that the engine won't even start and run with the universal NVA in place.