What Could Lift Caterpillar Stock?

Caterpillar (CAT) stock returned 75% over the past twelve months, against 16.0% for the S&P 500. The shares now cost 35.1 times the past year's profit, a ratio known as the P/E. The average P/E at the last twelve quarter-ends, leaving out readings above 100, was 22.0. With the P/E that far above its own average, where would any further gain come from.