well guys a while back my 4r70w went out so i decided to pu a 4r75w but now i am have problems i go about 30ft and the speed tops off and the truck cuts off, my question is do i have to reprogram the computer for the truck to work properly.

 

One of the changes in the '75 is a shorter Output Speed Sensor. Don't know if it reads voltage different or not but would think so.

 

so would i need to replace the speed sensor

 

I don't think a 4R70W sensor will fit due to the new design. I would contact a tuner and let him fix it through the PCM.

 

do you know of any.

 

I would recommend finding someone local first and if you can't start reading in the Chips, Tuners, and Programmers section. Lots of opinions in there and I'm not going to open that can of worms here

 

I did the same thing. I replaced my 01 4r70w with a 2004 4r70w. The output ring was updated so it now puts out 30 pulses per revolution where the old one only put out 6. The dealer said they cannot flash the ECM for this update. Only tire and gear changes. I didnt see anything where a tuner would allow this either. Any help?