What carseat fits best in an 05 Explorer?? I have tried different makes and models.?

You want a seat that is, first of all, appropriate for your childs age and size. After that, any of them are fine as long as they are in secure and fit the actual vehicle seat. When you fasten it in, use either the LATCH system or the seat belt, but never both. Put weight on the seat to push it down when tightening the LATCH/belt. To test if the seat is in tight enough, hold it by the edge right at the belt path. If you can move it more than an inch either direction it is too loose.

If you aren't sure if you have a good seat or have questions about it's installation, call your local police department. They should have someone on staff to help or can direct you to the right people.