If it's an automatic transmission it can stay in the car. Simply unbolt the torque converter from the flywheel and the trans from the engine. If it's a manual trans it's not that simple. You don't have enough room to slide the engine forward from the input shaft on the trans. It's easier to pull them both together.
You must remove the transmission are engine to replace the rear main seal.
Carefully
In my case, the whole engine needed to be removed.
No. You can remove the engine and leave the transmission in the vehicle.
A manual transmission does not have an oil pan.
Remove transmission oil pan for access to filter
On front wheel drive vehicles it is easier and quicker to remove the trans and engine as one unit. then you can separate them if you wish
You'll need to unbolt the torque converter from the flexplate. That's the only link between the two. Make sure to support the transmission before unbolting it from the engine.
Is this a standard transmission, or an automatic? automatic
Remove the transmission pan.
Check
you can remove the engine from the top by leaving transmission still in car