4 speed identification

I try to discourage guys from being too "number happy," why? Because (tell me again) how old is this gearbox? You don't think? that in 30-50 years, it could have a different gearset, or even just be part of a gearbox with other parts tacked on?

Determine for sure if it's an OD unit. The absolute certain / sure way to do that is put it into "4 speed 3rd gear" That is, starting in neutral, rotate the 3-4 shift shaft CLockwise. This puts a 4 speed into 3rd, and an OD into the OD gear

Now rotate the input shaft 1 exact turn, and watch the output. Less than 1 turn = 4 speed, more than 1 turn = OD box

Of course eyeball the tail shaft and make sure it's right for whatever you are going to put it in. Someone posted this the other day, I'd forgotten: "Big Block Dart" tech pages:

http://www.bigblockdart.com/techpages/techindex.shtml