Ok, I am not familiar with non turbo's. But I work on all sorts of cars all day everyday.

So I can tell you this much, It will most likely be directly above the front differential. That is the area where your axles come out of the transaxle(transmission if your a dummy).

Also you may have two speed sensors on this transaxle, once again I am not familiar with this unit. But alot of automatic transmissions have an input and output speed sensor, to detect the amount of slippage when its shifting so it knows if it needs to change adaptives to add or remove pressure from the band/clutch engagement mechanisms.

My description above is for an ouput speed sensor because most of the time people will refer to an input by calling is an iput speed sensor and they refer to the output as just a speed sensor since that is the one your speedometer works on.

Well, I haven't done a 420 a Eclipse, but if it's like the neon setup you are going to have a joyous time of replacing it. Hopefully that's not the case. That one is on the back side of the trans above the inner axle input. Right behind a damn brace which you will invariably have to remove.

Check there first.

The speed sensor is located in the rear of the trans, in front of the rear trans brace, it has one 10mm bolt in the top of the sensor holding it in place , remove the bolt and wiggle it up slowley, dont go pulling hard on it if you brake the little tabs that holds on the gear it will fall in the trans then you will have to pull the trans out, but wiggle it up slowly till you have a hold of the gear on the sensor. then pull with a little force and it should come right out . good luck

What he said, its located under the throttle body/battery area on the transmission. It has a 3wire plug going into it.

found it it was completly under the trans mount makin it almost impossible to see unless you get the car in the air...thanks for the assisstance everyone