Hi, another question about my vette. It is a 1981 built in 10/80. It has a steel leaf instead of fiberglass. The car is original St Louis car and I doubt it was ever replaced. Could it have been early production before the leafs were ready? I have the shop manual, but in general how do you evaluate sag? I might want to replace (and perhaps to fiberglass leaf?). What are pros and cons for the fiberglass leaf? Thanks.