I recently purchased a used John Deere P/N AL70191 Roll Guard and intend to install it on my tractor. Unfortunately, the fellow I purchased it from cut the attachment bolts with a cutting torch. I looked the bolts up and John Deere wants over $250 each for them! I was thinking of purchasing some Grade 8 or Grade 9 bolts for this application, but I'm not sure if there is possibly something else special about these particular bolts. I can't justify in my mind spending $1,000 for four bolts! Any advice would be appreciated. Does anyone know the Grade, diameter, length, and thread pitch of these bolts?