Anybody have any clues what this was used for?
(http://i1082.photobucket.com/albums/j368/wvabe/012-3.jpg)
Palnuts.
KO, palnuts are those stamped sheet metal cheezy nuts.
They used to use palnuts as lock nuts on connecting rods.
(http://www.alliedboltinc.com/productimages/Pal%20Nut.jpg)