12mm 12 point 3/8 drive impact wobble socket, for driveshaft bolts.
Ford commonly uses 5.5, 7, 8, 10, 13, 15, 18, 19, 21, 24mm, etc for most all bolt heads nowadays. Older Fords (mid 1990's) were a mish-mash of metric and standard bolts.
Some Rotunda specialty service kits are useful to buy on your own through your dealer, IF you will be specializing in certain work. Rotunda tools for rebuilding 7.5 and 8.8" rear axles comes to mind, as well as the OTC timing kit that costs around $700 and covers most all newer Fords. Diesel techs have certain specialty tools of their own as well.
Nothing anything less than a senior A tech needs to buy though.