2005 Ford E350 pan drop, gasket change, what fluid?

So I have a 2005 Ford E350 5.4l v8 super duty gasoline. Former budget box truck. It has 193k miles on it. Recently my transmission pan gasket started to leak and I'm planning to change it. Bought filter with gasket (5r110w transmission) 5 speed. Truck says use mercon sp on dip stick. Ford says they don't have SP anymore and to use LV. About 8 quarts in pan. I also read online that it's ok to mix.

I'm super worried though, I don't know what budget used when they did maintenance, if they did it. Is it safe to say that if I do a pan removal and clean it out thoroughly, change filter and then add mercon LV it will be ok? Also I'm confused on how many quarts it should hold 14 or 7.5?

My transmission is in awesome condition and I want to keep it that way, plus it's imperative that this truck works since I use it for delivery business. I will also start doing pan fluid change every 30,000, I from now on.

Do not mix. I don't care what they say., certain things in tranny oil act differently when mixed with others… & 7.5

Surprised dealer doesn't carry the SP should have at least one dealer who still has some in stock. Also try auto parts store to see if they have any thing equivalent. As far as the gasket the transmission originally came with a reusable rubber gasket black in color. If something else used you'll have to get the rubber gasket. Make sure the openings for the pan bolts on the pan are all flat. Also should be a small black plug in front of the transmission case take that plug out and move the torque converter around if lucky then the t/c might have a drain plug on it if it does then you can drain the t/c and use the LV fluid. Another thing check the cooler lines there's a secondary cooler line filter small coffee like can filter inside of that looks like a roll of toilet paper

Nope stores don't carry sp nor does dealer.