Navistar International Corp's Chief Executive Dan Ustian reiterated his interest in forging a collaboration with Oshkosh Corp following another wave of investor comments on the potential merger of the two rivals.

Ustian, speaking during the company's fourth-quarter earnings call, said there are some synergies in our two companies...(and)some collaboration we think might be beneficial for everybody.

He said that Navistar's commercial and defense vehicle businesses parallel similar product lines at Oshkosh. Ustian also indicated he sees an opportunity to supply Oshkosh with engines and vehicle chassis components.

Ustian said that some of Oshkosh's business lines, such as the company's JLG commercial lift business, do not make sense for Navistar.

Ustian's comments during the earnings call mirror comments that he made last week during an interview with Reuters.

This is the first time, however, that Ustian has addressed the Oshkosh issue since Owl Creek Asset Management founder Jeffrey Altman filed a disclosure noting his concerns about a merger. In that disclosure, Altman said Navistar needs to demonstrate the ability to derive significant value from synergies.

Owl Creek owns 8.5 percent of Navistar's common shares.

Billionaire investor Carl Icahn has been an advocate of a Navistar tie-up with Oshkosh. He owns about 10 percent stakes in both companies.

Shares of Navistar soared Tuesday following the company's earnings report, trading up 7.3 percent at $39.22. Shares of Oshkosh also recorded strong gains Tuesday, trading up 7 percent at $22.37.

(Reporting By John D. Stoll, editing by Dave Zimmerman)