I'm swapping from TBI to carb in a 1992. I'm also swapping rear gears to 3.42 from 2.73. Ive been reading, and searching, and finding the problems associated with speedo and carb/rear swaps in the newer models.

I got the speedo gear thing figured out. I have however been told that when going above 39t gears that a new sensor housing is required for the larger size gear, cost $55 - can anyone that has swapped above a 39t gear in a 1990/91/92 confirm or deny that a new sensor is required?

I also read where when the ECM is removed, no more issues, as the speedometer will not work at all anymore. Can't the ECM just remain intact, and remove the annoying SES bulb from the dash?

I also assume that one could replace the speedo itself with an older cable driven speedo, replace the sensor with an older cable sensor, and then be able to trash the ECM altogether. However, will an older model speedo look different in the dash, since the 1990/91/92 cars had yellow lighting, or is that just on the control switches such as heat controls?

Maybe this should be in the tranny fiorum - not sure - kinda applies to both

 

A cable driven speedometer won't fit in your dash. You shouldn't need the ECM to operate your speedometer.

 

Easy way to find out - unplug your ECM temporarily and see if you still have speedo! (Don't forget to reset error codes afterward)