Last May, the University of Michigan pulled out all the stops when it announced its drive, dubbed The Michigan Difference, to raise $2.5 billion. More than 1,000 wealthy alums and friends packed the glittering kickoff, while former President Gerald Ford — a Michigan grad — and his wife Betty were introduced as honorary chairs of the campaign. But for all the hoopla, the real drive had been under way for almost four years and had already netted $1.3 billion.