I believe the pin actually has 5 threads but that's neither here nor there.
You'll play hell trying to get one from McD and even if you could, they're like $12.ea.
So, here's your work-around. Schmelke has a similar insert for their QR pin but it requires about 30 seconds of machine work to adapt it to the McD.
You need to remove about 1/16" of the thread at the entrance so it will screw down over the blank section at the base of the pin.
Schmelke charges $2 for the insert IIRC.
Oh, I almost forgot. The external threads on the insert are metric.
12x1.5mm or 12x1.75mm. I'm not at the shop right now or I could tell you exactly.
*Back from the shop, it's 12x1.75mm.
Hope this helps.
