719.255732 Craftsman, Transmission

Howdy all! I'm trying to help a buddy out. He's got this old mower & thinks there's an issue with the transmission. He wants to know what lubrication it uses & how to check it. I'm wondering who made it. Is it a Peerless? A Tecumseh? Copilot says it uses SAE 30, But I find that hard to believe. I thought these manual transmissions use a very light grade of grease in them. I'm wondering if with the age it's just dried out on him. (1978) The owner's manual doesn't have any service info on the transmission I can find. I found that on the Sears site. Any thoughts out there?

There should be a drain plug at the lower part of the transmission.  
Probably a 3/4" headed bolt. 
 
There should also be another on the side of the transmission which would be the fill plug.
You'd fill fluid till it runs out..
 
I would drain and see how thick the fluid is.  It's going to be anywhere from 30 weight
to 85-90...    The old snapper gear box (walk behind) is the only one I know that took OO grease.
 
You should be able to tell the difference between 30 weight and the much heavier stuff..
 
Here's a link re fluids:
https://engineoiil-capacity.com/craftsman-mower-transmission-oil-type/ 
 
 
.