im looking into this fluid changing right now and ive got a couple questions.

1. i have a job 1 truck but i dont see an external filter. Do some job 1 trucks not have an external filter?

2. how many quarts of fluid do I need to buy if im doing just a drain and refil?

3. if my truck is currently filled with mercon SP would it be ok to top it off with Mercon LV?

4. Should i change the internal filter when i drop the pan?