I put the Ford AIS (heavy duty air filter set-up) in the F350 for $300 and it seems to work very well. In the F250 installed auto meter gauges and 5in Summit exhaust which really works good to monitor and make sure all systems are cool.
When time allows need to install the gauges in the F350 having bought them 2 years ago to put into the Excursion. Both the Excursion and F250 have had all their fluids replaced with Mobil1 syn. When the gauges are put into the F350 all it's fluids will also be swapped to syn.
It would be a good idea to add an in-line tranny filter and tranny cooler to help filter and cool down the tranny better, a gauge when towing big is key.
BTW, truck looks like it was very well taken care of. Wish the previous owner(s) of F350 was like yours!