94 bravada trans

I would like to know what tranny comes in a 94 Bravada. I would also like to know if a trans from a 92 s10 2wd truck would work. The problem I have is no 3rd or 4th gear it just started slipping.

You have the 4L60E. It's electronic with shift solenoids.
The '92 has a plain 4L60, non-electronic.
I don't know about running a non-electronic trans...the transmission module is going to wonder about the lack of signal fron the 21 wire pigtail.

The '92 version will require a signal from the PCM to lockup the torque converter. The '94 PCM won't deliver it without the rest of the solenoids and sensors being connected.

It is probably better to repair the current transmission and not that expensive. A set of new clutches, gaskets, and seals will set you back about $130.

The loss of 3 & 4 could be the"B" solenoid leaking oil through or stuck open mechanically or electrically. It could also be a failure to apply the 3-4 clutch. The 3-4 clutch piston could be stuck or leaking, or the 3-4 clutch pack could be slipping or the clutch hub may be grooved causing the clutch plate fingers to stick. Checking the solenoid is fairly easy. Everything else will require transmission removal.

I read that shifting manually when the slippage is first detected will save the internals with only the shift solenoid replacement being necessary.
Does that sound correct to you Blue Bowtie?