Okay just checked bolts from my 235 main caps.
Rear cap one has a TR and 3 radial lines. So old designation must not be a grade 5, it looks and seems much harder.
Number 3 cap bolt has a U on it both have thick heads, so they must be proper for the application.
Both are 3/4 hex and 9/16-12 , rear cap bolt head to thread is about 1.200, head to end is 2.436, head to.... means the head to cap contact area.
Number 3 cap bolt is 1.74 head to thread, and head to end is 3.00. Didn't check others but likely same, including short front ones.
