According to you guys, I gather this: Yes, it's an OD. And yes, it's a 4-speed.
. Does anyone have a picture of the inside of a 4-speed? If I am going to dump this one and want to find another, it'd be good to know what I'm looking for. .
You are supposed to be able to tell an OD box by the size of the retainer, but that doesn't do you much good if you don't know what to look for. I always just turn the shaft, see below.
I tend to refer to "regular" 4 speeds, that is "straight through" as "4 speed," and the overdriven boxes as OD. The OD box is still a 4 speed, but the old original 3rd gear has been re-worked for an OD.
You don't need to "see" the inside to tell an OD from a straight through 4 speed. I already explained above in another post...........put the box into 3rd gear by rotating the front shift shaft CW. Turn the input 1 turn and see what the tail shaft does..........less than 1 turn is 4 speed, more than 1 turn is an OD box
The thing is......you takes your chances. No guarantee that a box is in good shape. Otherwise, inspect as much as you can, and if the owner won't allow you to tear the side cover off, then move on, unless it's cheap enough.
I recently bought a 4 speed for 120 bux with a crossmember and the shifter body and handle. At that price "I don't care." Didn't even bother to inspect