Hmmm...the m656/xm757 5-tonners use the same winch as the M54 or M809 trucks, but specify a copper alloy (5315-00-880-5861 vs 5315-00-209-7979).
Always a spoiler out there.
It boils down to this,
The pin is designed to be the weakest part, don't substitute something that will make gears and u-joints the next weakest part in line.
Thinking people will make thoughtful choices,
If you have no source for the original part, you will find a reasonable substitute.
No, it won't be 100% original, but if this is for a working truck, which mine is, then 'field expediant solutions' become acceptable.
If you are doing a museum piece, then by all means purchase the two dollar gadjet with the ten cent function, as it will never need replacement.
If you have access to the specified items, so much better.
My caution stands, do not substitute a hard pin for a soft one, it is there for a very good reason.