It is a dedicated manual transmission cooler. The installation looks factory and if it's after market, it's very well done. Port in each PTO cover, rubber lines to what could be an electric pump on the top side of the cross member, driver side. Steel lines from the cross member/frame rail connection to a small dedicated cooler in front of the radiator on the passenger side, looks like they could be lines for an automatic, not just straight sections, they look like factory lines, I'll post pictures later. Truck was used for towing horse trailers. It also has a Mitchell splitter with a temperature probe (not connected).