The 602199 (11 off) is listed as 5/16 UNC x 11/16. The 2 at the rear are just listed as 'special', no length given. Longer makes sense as they have to go through the brace plate. Since these all have a tendency to loosen by them selves I suggest you use bolts with integral washers with serrations on them, or at least some sort of washer - internal stars? IIRC they take < 10 ft/lb to prevent squeezing the gasket out, and most 1/2 drive torque wrenches will not be accurate down at this level - I use a 1/4 drive wrench that peaks at 25 ft/lb.