I use the two head bolts like the manual shows, and bolt a small piece of 2 inch angle iron under them with holes drilled to attach a chain. That gives me more thread engagement than trying to use the head bolt to attach the chain directly.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!