Genuine Ford Fluid XT-M5-QS Full... https://www.amazon.com/dp/B000NUES82?ref=ppx_pop_mob_ap_share
The Ford xt-m5-qs is the most recommended transmission fluid, but others swear by Redline - https://www.flyinmiata.com/default/redline-mtl-synthetic-gear-oil.html
Super easy to do yourself. And you should do the differential fluid as well of you have it on jacks.