you can probably find it at your local autozone
free download for a 1990 Chevrolet blazer owners manual
it's manual
How do you open the hood on a 1990 mercedes
On my old Patrol ('90), standing, facing the vehicle, open the hood and to the left, just behind the light, there is a little aluminum plate, should be on there.
It is inside the owners manual.
Ebay motors has them.
Try google
For the gearbox or engine? and there both in the engine bay.
The short answer is yes. Both the 1989 and 1990 models use the RS5F50A manual or RE4F02A automatic transmission.
It says 11 gallons on my owners manual.
Lost Patrol was created in 1990.