I'd recommend going with whatever you find the best deal on. The potential for low lube failure is the biggest concern for these. Every other concern or issue pales in comparison. Even the 5th gear nut falling off doesn't frag the entire inside of the tranny like a low lube failure does. Countershafts just don't break...Granny gear options are pretty much irrelevant.
I wish I had pics of the mangled, melted mess that I found when I opened this tranny up. It was pretty impressive. When you find one, overfill it. Hell I'd like to see a dipstick option for these so you can overfill it and check it often.
Rene