I have 2003 F-150 4.6 w/ AC.
For accessory belt www.motorcraft.com gives me JK6-996E as a part number.
However, if I check the http://www.fordinstallersupport.com/...s/belthose.pdf I'll get JK8-996-AA as a part number.

Amazon tells that JK8996AA fits my vehicle, but for JK6996E it tells that it won't fit.

I know that Amazon is sometimes unreliable, but Motorcraft should know better.

Which one is the correct part number? Should both fit?

 

Why not just go to an AutoZone, Oreilly's, Napa, Advanced Auto Parts, ect? At least that way even if you get the wrong belt, you can easily take it back and get the correct one.

 

JK6 is for 6 rib pulleys, JK8 is for 8 rib pulleys. 996 is length - 99 6/8". Non-AC would be a 803.

 

Just look under the hood, - Alternator is right there. See if it has the 6 or 8 rib. I'm guessing it has the 6 rib,- could be 8 tho.
But yea, -easy to confirm yourself just looking at it. Unless you can't count that far..

 

When I plug the Motorcraft # into the dealer site here ---> http://www.bluespringsfordparts.com/...150-parts.html

It says that it doesn't fit that application...

I think Amazon is right about the second part. Try searching that site to see.

 

Thanks - yes, my truck is 6 rib, so JK6996E will be a belt for my truck.

I can count at least to 10 as I have 10 fingers but I could not decode Motorcraft part number. Now it is obvious that JK6 is for 6 and JK8 is for 8 rib pulleys

Also I did not realize that 8 rib pulleys were a factory option for F-150 4.6 XLs!

 

Yea, 8 ribs were for the larger amp alternators, like say for municipal vehicles that need the extra amps. Police vehicles, ambulances and such. They must have been a available option for your model year.

A large amp alternator requires better traction, more engine power and a belt that won't slip which is where the 8 rib is necessary.