Longhorn is right, if it has 4 bolt side cover it's a Muncie non synchro 1st.
I've had them apart before. The main issue with them is that they can rip the 3rd gear synchro hub out. It's held in by a snap ring that pops out of it's groove. On my current 63 truck, I just cleaned up the snap ring groove with a Dremel and put it back in place. It works fine.
They are dead simple inside and a great first transmission rebuild to learn on.
I just bought another one at the swap meet last week to rebuild and swap into my truck.
I got all of the parts to rebuild it (bearings and seals, etc..) at my local transmission shop for 70 dollars.
I will rebuild it in a week or so and take pictures of everything along the way and do a tech post on the process.