The F-35 program is spread across hundreds of vendors with representatives grabbing a piece for their constituents. I wouldn't be suprised if different diameter

The F-35 program is spread across hundreds of vendors with representatives grabbing a piece for their constituents. I wouldn't be suprised if different diameter o-rings are coming from different suppliers. This is a strategic approach that both jacks up the price and gives you plenty of powerful allies who will fight to keep the program afloat. They could very put such an aircraft together at half the cost and time if cost and time were targets for the people deciding to fund this.