IIRC ARDIC doesn't do much, if any, major production work. In a lot of cases, ARDIC actually does serious indigenization work (either via original R&D or reverse-engineering), and then licenses out the know-how to others, which could include HIT or the private sector.
In fact, of Pakistan's SOEs, HIT does the best job now (followed by NRDI) in looping in the private sector for work. Sure, they don't take platform-level stuff (e.g., tanks, AFVs, etc) from the private sector seriously and would assemble those at HIT. But they'll outsource quite a bit of upstream work (specific parts, subassemblies, etc) to private companies.