NEW YORK ( TheStreet) -- The last time that corporate rabble rouser Carl Icahn went after an industrial manufacturer -- in 2007, when he tried to buy auto-parts maker Lear ( LEA) -- his efforts failed. In disclosing his 9.5% stake in truck-maker Oshkosh ( OSK) Thursday evening, Icahn stopped short of calling it the first move in an attempted takeover bid. Instead, his filing with the Securities and Exchange Commission, required whenever an investor builds more than a 5% stake in a public company, noted only that Icahn believes Oshkosh shares are "undervalued" and that he and his firm "seek to have conversations with management ... to discuss enhancing shareholder value." Still, news of Icahn's play pulled in the arbs and other traders Friday. Shares of the Wisconsin company, best known for building armored personnel carriers for the U.S. military, shot higher by 12% in late morning action, changing hands at $32.56 on volume of more than 4 million shares during a normally sleepy pre-July 4 trading session. In his filing with the Securities and Exchange Commission, Icahn said his affiliated funds paid $129.5 million for the nearly 8.7 million shares, including brokerage commissions and premiums for underlying call options. (The shares that back those options are also included in the 8.7 million total.) Before Icahn's disclosure Thursday, Oshkosh shares were trading at about $29, good for a forward price-to-earnings multiple of 9.14 (as judged against 2012 earnings forecasts). By comparison, rival truck-maker Navistar ( NAV) trades at a 7.9 multiple. Terex ( TEX), a construction-equipment manufacturer, has a 12.4 forward multiple, while tow-truck company Miller Industries ( MLR) comes in at about 12.2. Oshkosh had made hay over the last two years after winning a lucrative contract from the Pentagon to build a line of durable all-terrain vehicles specifically for fighting in the rugged landscape of Afghanistan. The win, which came as something of a surprise in the defense-contracting industry, was instrumental to Oshkosh, which was then facing financial difficulties, having acquired a crane-making company at the height of the boom. -- Written by Scott Eden in New York >To contact the writer of this article, click here: Scott Eden. >To follow the writer on Twitter, go to http://twitter.com/ScottEden. >To submit a news tip, send an email to: firstname.lastname@example.org.