Changing trans selenoids

Recently had a code for solenoid b to be replaced minor slippage from first to second at start off. Wondering if someone can tell me roughly how much trainny fluid will be needed and what would be the best fluid to use since I don't know what is already in there. I bought all 3 selenoids already and a new filter with gasket. Need help ty.It's a 2000 SR5 with the 4.3 4x4

 

from what ive found it looks like 4-5 quarts if you just drain it, if the pan comes off its around 7-8 quarts total. The type of fluid you want is any automatic transmission fluid that is Dexron III