5R55S - 5R55N - 5R55W

just as the title states, the Ford 5R55 Transmission has four versions. Ford 5R55 can have an N, S, or W behind those numbers.

The 5R55 is a rear-wheel drive 5-speed that appeared in 1999 and later vehicles.
The 5R55W came out in the 2002 and later Ford Explorer and Ford Ranger models.
The 5R55N appeared in the Jaguar S-Type and Lincoln LS and in 2002 in the Ford Thunderbird.
The 5R55S without the Select Shift is used in the 2005 and later models of the Ford Mustang. In 2003 the Thunderbird and Lincolns switched to the 5R55S that had the Select Shift (which allows drivers to shift like a standard without the clutch).
Although the 5R55N is very similar to the W or S models, only a few parts are interchangeable.