* TH700-R4: This was a 3-speed automatic transmission, likely found in models with smaller V8 engines.
* 4L60: This was a 4-speed automatic transmission, likely used in models with larger V8 engines. This was a newer design for the time compared to the TH700-R4.
To know for certain which transmission was in a *specific* 1989 Suburban, you'd need to check the vehicle's build sheet (if available), the VIN number (through a decoder), or look at the transmission itself (although this requires some mechanical knowledge).