Sometimes, I don't understand Mr. Market. Just plumb don't get how his brain works.

By and large, investors reacted positively to Oshkosh's (NYSE:OSK) Friday announcement that things aren't quite as bleak as we once thought. According to management, Oshkosh will probably max out or exceed its previous fourth-quarter guidance -- earning $0.65 per share or more, and bringing the company's total take for the year to $0.98 or more. 

That doesn't sound like much, but also recall that last quarter, Oshkosh snipped $2.33 per share from guidance when it wrote down the impaired assets of its European garbage-truck business. But for that loss, we'd be looking at closer to $3.31 per share, and a price-to-earnings ratio of around 4 on this stock.

More bullish still were the details Oshkosh provided on its increased guidance. Management expects to pay down its debt to as little as $2.8 billion -- a reduction of $180 million in just three months -- which suggests an unforeseen surge in cash generation at the company. Cash flow -- exceedingly weak of late  -- is now called "strong," and management is husbanding its cash by "selling excess inventory, rationalizing production and pursuing receivables initiatives."

The expected ...
Wall Street's initial response to all of this good news was predictable -- the stock surged nearly 40% through Tuesday's close and even gave rival Terex (NYSE:TEX) a brief lift on Friday. Yet today, as of this writing, Oshkosh is tumbling 7%.

... and the not-so-expected
While the initial reaction makes sense, today's does not. Friday's guidance was only the first bit of good out of Oshkosh in recent days, you see. Yesterday, we learned that the Pentagon is moving forward on awarding its long-awaited JLTV program. From what I hear, Oshkosh is a leading contender -- along with partner Northrop Grumman (NYSE:NOC) and other big names such as General Dynamics (NYSE:GD), Lockheed Martin (NYSE:LMT), and Navistar (NYSE:NAV) -- to participate in this multibillion-dollar contract. And this morning, we learned that Oshkosh landed a $180 million-plus order to provide hundreds of add-on armor kits for the Marine Corps' Medium Tactical Vehicle Replacement (MTVR) fleet.

I think that the potential for billions of dollars of new JLTV revenues, coupled with an actual multimillion-dollar defense contracting award, provide more concrete reasons to own Oshkosh than a single reassurance from management that "really guys, things aren't as catastrophic as they seem. Disastrous at worst."

But hey, I'm just a Fool -- and an Oshkosh shareholder. What do I know?

What's a JLTV, and why could it give Oshkosh's stock a jolt? Find out in:

Fool contributor Rich Smith owns shares of Oshkosh. The Motley Fool owns shares of Terex and has a disclosure policy.