GRAPEVINE, Texas — Truck and engine maker Navistar Inc. has tweaked the designs and specifications on its Class 8 ProStar and TranStar tractors in order to lure fleet customers with what its management sees as better ways to comply with recent federal regulations.

Billionaire investor Carl Icahn bought a 9.8% stake in Navistar International Corp., making him the second-biggest holder in the company, Bloomberg reported.

The trucking joint-venture between Navistar Inc. and Caterpillar Inc. will become a Navistar subsidiary, the two companies said.

Navistar International Corp. said it plans to sign a lease agreement that would give the company a third plant in Alabama.

Truck maker Navistar International Corp. reported a jump in quarterly profits boosted mainly by a tax-related adjustment and said its sales have accelerated but are still held back by problems with components suppliers.

Navistar Inc. said that it will permanently close its heavy-duty truck manufacturing plant in Chatham, Ontario, which has been mothballed for two years because of a labor dispute.

Navistar International Corp. said late Tuesday it will close its truck plant in Ontario, Canada, that has been idled for two years due to labor issues.

Truck and engine builder Navistar Inc. said that it has begun selling aftermarket parts on Amazon.com.

Navistar International Corp. spokesman Roy Wiley has concluded a 13-year run with the Warrenville, Ill., truck and engine maker and an overall career of 59 years in newspaper journalism and public relations, retiring June 30.