I'm about 40% through a body restore on my 66 mustang. Rust has been a constant sight, but none of it has affected the stability of sheetmetal until today. There are two rubber capped holes on either side of the gas tank just above the left and right longitudinal frames. Both are rusted. The left one has suffered metal fatigue. What are these holes for? I thought they might be drains, but they are higher than the lowest part of the trunk (gas tank). Can I just cut the affected sheet metal out, and find a bigger rubber plug?