One of the most "popular" is the Transmission Range Sensor (TRS), formerly known as the neutral safety switch (NSS).
The TRS is known to fail and cause all sorts of very weird and unusual symptoms - kinda like gremlins infesting the electrical systems.
See "Related Questions" below for more about the TRS
Oh yeah, there's the TCC so, but you don't hear so much about that one...
No. 2000 Taurus and Sable are the only interchange.
where is the transmission speed sensor located on a 2005 ford taurus
The critical piece of information is missing from the original question: which sensor of the dozens of sensors in the typical Taurus / Sable
It will fit in the same year Taurus and Sable, nothing else.
On the transmission.
The speed sensor on a 1999 Taurus is on top of the transmission. It is located directly under the number 2 cylinder.
Inside transmission
There can be as many as 6 speed sensors. The transmission has two speed sensors, one called a VSS and one called an OSS. If the vehicle has anti-lock brakes, each wheel hub will have it's own speed sensor.
No, a Generation 2 (1992-1995) Taurus/Sable Windshield will NOT fit a Generation 3 (1996-1999) Ford Taurus/Sable.
The speedometer is driven by the vehicle speed sensor. See "Related Questions" below for more about where to find it, and how to replace one.
Most likely you have a problem with the torque converter or the valve body in the transmission. If you have around 85,000-120,000 miles on your Sable/Taurus, this is a common issue. Having a transmission specialist look at the vehicle is an expensive but necessary pitfall.
My 1995 Mercury Sable with 3.0L has that trany in it. So I'd say yes