large halyard shackles
 

I'm looking for an unusual large halyard shackle or D-shackle: a 1/2" pin, with an inside width of at least 1 1/2" to accomodate a wide headboard.
Most shackles this width have pins greater than 1/2".
Any suggestions?

The ronstan 1/2" wide D (RF641) is almost there. It has an inside measurement of 1 1/4". You might be getting in to a situation where something will have to be made (such as a pair of linkplates).