Gear swap question

I have a 2004 Expedition (I know, this is a mustang forum. I'm getting there) Anyway, the expy has 3:73 gears. Stock it had 17" wheels and now it has 20". So, I'm going to put 4:10's in the expy. The 3:73's would really wake the 97 pony up going from 3:08's. The question is, they are both 8.8 gears. They should fit the mustang right?

Yeah FoxRod, the expedition has 3:73's stock. It went from 17" to 20" tires and the slightest hill on the highway sends it right to downshifting and I get 14 mpg on a good day. Sounds crazy but I think the 4:10's will actually improve my mileage on the highway because they should put it back into the power curve that was engineered. As far as the stang goes, it has 3:08's at the moment. Just did a P.I. head swap over the summer and those 3:73's along with a shift kit will wake it up.
Rocky, I'm pretty good at most things but due to the close tolerance of gears, I don't mess with them. I will have them professionally installed. I believe he did mention something about a rotunda tool. I just heard blah, blah as long as they get put in. Thanks to both of you for your input. I like to be sure of things before I throw my money around.