21534 Meyer MDII A-Frame 36" Lift Chain (single)

Genuine Meyer Chain # 21534.

This chain is used on the ST and C-series MDII and Plus mount plow setup in conjunction with the A-frame. Attaches to the A-frame using U-bolt # 8518001026, Nut # 8501001007 and lockwasher # 20328. Some of them have the chain welded fast, this is for the style that bolts on. 

This is a 5/16" x 36" chain.

You can find a breakdown of related parts at this link.