The jumper struts are not needed. Actually you are probably better off without them. Sailing without them allows the mast to bend more, making the boat more forgiving in a puff. The regular stays, that connect to the chain plates and pass through the regular spreaders, are sufficient to hold up the mast.
If you insist on putting them on, there is a tang on the mast that bends outward, slightly, just like the ones that connect the stays to the mast, but "opening" upward. The stay (if I remember correctly)has a fork like attachment that went on both sides of the tang, with a hole in the middle for a clevis pin.
J .P. Clowes
Eastern Great Lakes Regional V.P.