* TH400 3-speed automatic: This was a very common and robust transmission in heavy-duty trucks of that era.
* 4L60E 4-speed automatic: This was also a possibility, though perhaps less common than the TH400 in a 2500 Suburban. It was more common in lighter-duty vehicles.
To know for sure which transmission is in *your* specific 1994 Suburban 2500 4x4, you need to check one of the following:
* The vehicle's identification plate (usually located on the driver's side door jamb): This may list the transmission type.
* The owner's manual (if you have it): This would specify the transmission for your specific vehicle configuration.
* The transmission case itself: The transmission case usually has identifying numbers or codes cast into it. You could compare these to a parts catalog or online database.
* Your vehicle's title or registration: The transmission may be listed on these documents.
Without looking at your vehicle's documentation, it's impossible to say definitively.
