I have several of these on my shelf, been there for years. Anyone know what they are? Thanks in advance for your help (the top reminds me of a plow bolt)
For sure - some quite exotic and expensive type fasteners. Could be used most any place where you attach equipment. 3-point, FEL attachment pins. Would require countersink anywhere they could be used.
JMHO - they came with some very specific/specialized piece of equipment.