It hasn't been dull at Winnebago industries; Inc. in 1971, the Forest City, Iowa, maker of recreational vehicles was the year's hottest stock, up 462 percent. Then came the first gas crunch and, as Winnebago was getting going again, the second gas crunch. Revenues dropped from 1978's $229 million to $92 million and a $13.5 million deficit in 1980. That was when founder and 45 percent owner John K. Hanson came out of retirement, laid off a mob of M.B.A s, and got the company profitable again. In the process, his son John B. ended up leaving the company