changing differential oil

[dropped72shortbed]

first time doing this, main reason im pulling the cover is just to see what gears i really have. previous owner says 4.11s, but hes been wrong on other stuff. it does rev pretty high on the freeway, i think the truck tops out under 100mph. so maybe they are 4.11s

anways what are the steps? just pull the cover and let drain? then do i need a new gasket for the cover, what weight oil? when im done just bolt the cover back on and then refill the oil from a fill hole up top? any idea where the hole is? im know is kinda hard if i cant tell you want rearend it is, but ill take pics while im working monday and show em to the board. im sure i can figure it out myself.

sorry, i must have been slacking off in high school auto shop cause i never did this chore.