This shows (top picture) the six rivets on each side of the seat "V" area that get replaced with 6 new bolts. Six bolts on each side of the aircraft going lengthwise along the fuselage in the seat "V" area to strengthen the main landing gear frame.
The bottom pic shows the six bolts going perpendicular to the fuselage, with the bolt heads now on the inside of the fuselage and the nuts on the outside. These six bolts on each side of the aircraft had to be removed early on in the service bulletin to gain access to the six rivets that had to be drilled out on each side. The picture shows 6 new bolts now going back in, perpendicular to the fuselage, completing the service bulletin main landing gear fasteners.