77 manual tyranny drain and fill pug

I have a 77 G10 Chevy with a 3 speed manual transmission. I got slider door with windows from junk yard and just painted it with plasti dip artwork on the outside and fixed up the inside. I will post pics later on

But now just getting to work on it and today while fixing rust under the van I noticed it might be seeping tranny fluid. I drive it quite a bit.  I notice a little fluid seeping.

It looks like a very very slow seeping not a big leak, but I am thinking of going on a road trip so I want to top it off. They guy i bought the truck from did not care for it properly, it runs well but  after driving it for a year I think i should make sure that fluid if full.

I want help to confirm if I am right in see what is the fill and drain plug before I start messing with it. I also need to know what fluid is needed for a 77 manual  

Is this the fill plug?  on the right passenger side of the tranny about half way up. but the thing i see there has a square headed bolt.




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is this the drain plug... hard to get my camera to get a straight on pic because of a horizontal frame bar but it is on the lowest part of the back of the tyranny in the center. its covered in crud but you can see it.



and theses are numbers writen upside down on the tranny




Any help appreciated. is it quite a great truck, I want to keep it on the road.

Ok,,,,,,this section is for the Earlys,,,,,,,and your post will be moved over to the Early Enough forum tomorrow,,,,the ones with hoods, and you can continue from there,,,,,,,choose 640 for resolution so your pictures dont get cut off,,,,,,,that sure is the fill plug for your trans,,,,it sure would like to have 85-90w oil put in there until it runs out the hole,,,,,,no drain plug,,,,,got to suck it out through that hole if you want to get rid of old oil,,,,,,,