ID stock 3 speed - not RAT RAN or HEF but RAB? Orion?

[thegreatjustino]

Anyone ever seen a stock three speed transmission with an RAB tag instead of RAT, RAN, or HEF?

The transmission is cast with the name Orion in the case above the front shift tang.

Curious if anyone knows anything about this. RAB also doesn't show up in the ID chart here

http://www.davidkeetoploaders.com/3speedidchart.htm

 

[DirtDonk]

Don't recognize that angle bracket under the top cover bolt either. (maybe a tie-down for the wiring harness?)
I was going to ask if it had a drain plug on the bottom, thinking it might be a very early model. But that last image showing the Ambient Switch tells me it was a specialty version from a '73 with the Ambient Sensor in the door pillar.

Didn't know if they had a different designation, but the other boxes did not have the hole or even a boss that I know of for that switch.
Maybe Viperwolf knows, since he's dealt with information on those model years a bunch.

Paul

 

[Broncobowsher]

I don't remember the details, but the switch is a top gear switch. Has something to do with emissions. Yea, the manual transmission is tied into the emissions system, in the 70s. EGR enable or something like that?