Okay, here's what I'm working on. It's a picture of an Air Tractor (crop duster). The space is really tight. It's two bolts facing aft holding the A/C housing to the drive shaft housing assembly. I should have measured the space between the end of the one bolt and the head of the other, but I didn't. And that third bolt below has to come out before I can get a socket on the other two. I can't get a box end wrench on the inside of those two, not enough clearance, but a socket works. And I'd rather not grind on my sockets (at least not that set given to me by my grandpa who passed). I'd rather just have an extra handy ratchet.
That being said, when I stopped by harbor freight this afternoon I picked up that long handle t bar 3/8 drive ratchet. The head is slightly bigger than the snap on one, but man is this thing small! I think it'll come in handy in other situations if not this one. I bought a set of the square drive to hex adapters as well for ratcheting wrenches if that doesn't work out.
The measurements of this t-handle 3/8 ratchet are 0.53" where the socket backs up to one of the thirds not obstructed by the selector (tightest fit) and 0.645" to the back of the selector where it will actually be when I'm ratcheting. Which compares nicely to the snap-on where it's 0.495" and 0.54" respectively (I think on that last one anyway if memory serves correctly). And the length of the ratchet handle comes in at a whopping 3.75" from head to handle end!