Mining Boom Pumps Up Terex

And the supply response from tire makers could auger other operational efficiencies winding their way through the supply chain.

"For Terex, it's probably enough to move the earnings needle," says Morningstar's Kearney, who adds that the stock is attractively priced at $80, below what he considers fair market value of $86. But with the firm's very late-cycle mix of products and good earnings growth, the stock could have a lot more upside.

Likewise, others see profit potential in owning Caterpillar.

With Caterpillar, "the price of the stock tends to move with the earnings, not ahead of it," says Alexander Blanton, an analyst at New York-based Ingalls & Snyder. He projects earnings of $5.85 a share in 2007 and $6.75 in 2008, which is at the high end of the range from Wall Street analysts.

Blanton says the stock has typically peaked at a price-to-earnings ratio of 14.5. If that relationship repeats, then the stock could be worth close to $100, vs. about $76 recently, and that doesn't count the two to three more years of good earnings Blanton spies ahead.

Other analysts are somewhat more cautious.

Baltimore-based Stifel Nicolaus downgraded Caterpillar's rating to hold from buy Thursday.

"Any more oil price strength, as in the 1970s, may be destructive for the rest of CAT's business now as it was 1977 to 1981," writes Stifel analyst Barry Bannister.

Even with that caveat, Bannister says Caterpillar's stock is worth $81, almost 10% above the current share price. Part of the reason for the downgrade may be chalked up to Stifel's policy of restricting buy ratings to stocks likely to outperform the S&P 500 by more than 10% inside 12 months.