i have an oem body kit that will be going on my wife's 04 focus. it includes the front lip, side skirts and rear lip. the rear lip is of no use to me because it is for hatchbacks. will a 05-07 rear bumper fit an 04 without issue?
They are not a direct fit. I have seen only one person who has changed the rear of his sedan and he had to do the whole thing (trunk, bumper, and taillights). The front and rears are not interchangeable between first and second generation Foci.
If u have a sedan rear sap bumper u need a 05-07 trunk lid and tails to fit. A local already converted his. Its only 4 bolts on the trunk and 2-4 for the tails come on it looks sweet! Just wait for the parts to come up cheap then swap them. I've seen trunks (very clean) for $50 and a pair of stock tails for $40.
If this is a route you want to take, salvage yard may have the taillight and trunk for a pretty low cost. If your lucky, you can even find a trunk in the color of your sedan. It would look awesome if you're willing to put the time into doing the swap.