Terms of the acquisition weren't disclosed but the O'Gara Group said PDI's former owners would continue to manage day-to-day operations of the company.
PDI makes armored passenger vehicles for a variety of clients, including the U.S. State Department.
"We are very happy to join with the O'Gara team, among the pioneers in the vehicle armoring business," said Dennis Hendrix and Jorge Resendiz, the former owners of PDI. "We look forward to realizing the benefits of combining the relationships and resources of both organizations to expand our role in the vehicle armoring business."
With the acquisition of PDI, the O'Gara Group gains 30,000 square feet of manufacturing space in San Antonio.
The company said that in addition to buying PDI, it has also leased additional manufacturing space for its operations in Ohio.
"We are delighted to be back in the business of armoring vehicles in our own facilities," Wilfred "Bill" O'Gara, chief executive officer of the O'Gara Group.
"It has been over 10 years since we departed the business after the sale of O'Gara-Hess and Eisenhardt Armoring Co. The acquisition of PDI expands our relationship with the U.S. State Department and will complement our new facility in Fairfield, Ohio."
The O'Gara Group, with operations in Europe and Mexico as well as the United States, supplies security and defense products and services to governments and commercial customers to protect customer personnel and assets from terrorism, crime and other threats.