Recently purchased 04 F150 4.6L/w 84k. Changed plugs (Motorcraft) and coils, MSD 84248. It took me longer to change the coils (and more sweat equity) than the plugs! The MSD connector was too tight. I could barely push the harness connector on them. The red insert that holds the pin connector would barely fit the MSD coil, let alone get passed the orange neoprene seal!
I have used these coils on a 03 4.6L Mustang and had no problem. Really stumped on this one?
Truck runs great and pulls 19.5 on my vacuum gauge at idle.

 

So did they work or not?

 

^"Truck runs great and pulls 19.5 on my vacuum gauge at idle"

 

could of used a little Dielectric grease on the seals..

 

I used digrease on the seals, inside edge of the MSD connector, etc. A couple of times the red lock connector separating female contacts on the harness side pulled out. The old Motorcraft coils fit fine. Liv n' Learn.

 

Gotcha