Transmission Fluid Fill

Hey guys and gals,

I've been looking for definitive information about how to fill transmission fluid and can't find the answer.

I have a /6 904 transmission. I've seen some pics that show a drain plug on the pan, but mine doesn't have that. I've also read about a filler tube. Is that the dipstick tube (one in the same)?

Thanks in advance,

Jim in Jax