Let me start off by saying I dont drive a F-150 (my dad does tho!) So anyway, Im here to get suggestions on my transmission for my 1982 Ford Granada 3.3l Inline 6, My transmission has recentley started to slip in all gears right around 35mph. I imediatley took the back roads home only going 25mph. When I got home I pulled my dipstick, The fluid was red and full, and didnt smell to burnt. (I have smelt way worse) What causes transmissions to slip in all gears around a certain speed like 35mph? Im not sure if it will help or not but my transmission is either a c-5 or c-4. I believe some old f-150s had Inline 6's and may of had a c4 or c5. I turned to this forum due to the fact that this is the only transmission forum active that I could find. I hope you guys can help me. I need to get back on the road