Standard transmissions are different from automatics, some newer ones do use automatic fluid, olders one and some newer ones use gear oil.

but i'm sure that all of them have a plug on the side of the transmission, this means you have to get under the truck to see it and fill it.

some plugs have a big square head that is easy to see, other have a plug that that is indented and is square so you can put a ratchet in it. both fill the same way, you can use a squeeze
type bottle and fill till just the bottom edge of hole, or you can rig up a funnel with a hose and fill to the same point from the outside, just make sur which ever way you do it the truck is level.

go to your local auto parts store and get a haynes manual for your model truck, they have some pretty good info in their books.