Below is a link for a 2005 F-150 Paint Chart and Part#'s. If you scroll all the way down youll see theres 2 different tan interior colors.. 1 is mediun pebble and 1 is dark pebble.. I dont know if these are the colors you need but hope it helps.. If part#'s are incorrect/old you can contact Tasca Ford they will give you the current part# and may even suggest the correct color.
I happened to have ordered Medium flint for my truck in preperation to buying my gryphon so i can paint it, that was before i found out they now come color matched instead of black. Well i got the MF it was $19.00 to my door for 6oz. Unfortunatly on the cap it looked similar to my interior but after testing a piece of plastic it turned out to be no more than just grey.. So it may be trial and error.. You could always do what everyone else is saying..go to a paint shop..maybe your speaker grills are tan also, you can bring them in for a match.. or anything thats the same color tan. Hope this helps!!
http://www.fcsdchemicalsandlubricant...2005-paint.pdf
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2004 Scab Lariat
Leveling Kit, 20"OEM's, Magnaflow SI/DO Exhaust, AirAid Jr Intake Kit, K&N Drop in, PHP Gryphon.