I have 98 el falcon sapphire 4.0L and i am lookin for diff gears 3.7 or 3.9. i was wanting to know what car can i pull them out of, other than an EL.

And i was wanting to know what is meant by a 75 series and a 78 series, because i was told 78 series will fit perfect for my car, and 75 series will fit but its not the proper type?

78 series out of a pintara.