| Re: oil pan gasket
Practically speaking, the oil pan CANNOT be removed on the Northstar engines with the engine in the car.
The exhaust crossunder pipe goes directly under the oil pan from the front bank of cylinders to the rear. It's so close to the oil pan that there's no way to get it off without removing the engine from the car. The exhaust pipe goes between the engine and transmission so it can't be removed without separating the engine and transmission out of the car.
Some garages have attempted a hack repair by cutting a section out of the exhaust crossunder pipe, removing the pan and then rewelding the section of the exhaust pipe back in. Since that's a double walled pipe and stainless steel it's not easy to do correctly.
Technically, I guess you can remove the pan in the car as some service techs will drop the tranny from the car leaving the engine in place and then remove the exhaust crossunder pipe for access to the pan, But it's a toss up as to whether this is easier than dropping the cradle and separating the engine and transmission outside the car.
In any case, you aren't going to get the oil pan off a Northstar with the engine in the car by taking a lot of parts off unless you take the transmission off. | 
