I suspect these springs aremostly tossed when clutch or other work is done along its 50+ year life.
Any form of a spring that just holds fork away from TO bearing so it does not constantly press against pressure plate and or rattle while driving.
My truck shifts fine other than when I recently left a cruise and felt I really needed to push clutch all the way to floorboard to disengage. Adjusting the rod about 1/8"-1/4" resolved that.
FWIW this is the one size fits all (# 10), aka cut and bend as needed depending on engine application, that LMC has. It does not appear to be like the pic in post #10 above.
I assume this spring would be stretched forward of clutch fork. I will look again for a hole in frame that given the "correct" spring would attach. But at the end of the day any spring attached somewhere should suffice. Given they are $3 I will add one to the next order I make at one of the parts suppliers.
https://www.lmctruck.com/1967-72-che...tch-components
this appears to be the spring post 10 shows
https://www.classicparts.com/1963-72...20group%20%231