Were 4-speed tranny's blue?

Hey everyone I had a question about mustang gearboxes. When I took mine out I noticed it was blue and had yellow letters on it. I figured it was a previous owner and I painted it gray like most other tranny's. However I saw another 4-spd for sale and it was also blue with yellow markings. What gives? If it's owners doing this then why the yellow markings that look like part numbers? Any info is much appreciated.

The Stang top loaders also are what is used in the AC Cobras (short shafts). I have seen a lot of top loaders, I mean a lot by being around a lot of SC 427s and I have never seen one painted blue with yellow letters. All of them have been bare cases. Soo, my bet is the previous owners have painted them for street rod use or just to pretty up the underpart of the cars. Now the real experts can put in their 2 cents.

Brian