Requesting help with a Speedmaster 321 105012-66 CB question

Hello all,
I would appreciate it if someone here could help me understand the situation with a 321 that I bought as a refurbished watch from a Tourneau dealer about 10 years ago. Here are the basic facts: the movement has a serial number of 25443446 which I think indicates a 145.012 from 1967; the case back is marked with 105012-66 CB, and with what appears to be a factory marking of 145 012 SP; the case was overly polished when I bought it, there are no facets on the top of the lugs, but the sides of the lugs look much thinner than my HF cased 861. I'm confused by the inside case back markings. Is this a 145.012 reference 321 that somehow got a CB-marked case back somewhere along the way? Or is there another explanation? Thanks for any help with this, Mark

There are others...

http://m.ebay.ca/itm/121907760935

I think the theory was that it was during transition where old case backs were stamped with the new reference number.

Thanks for the information above, I didn't realize there were dual marked CB backs. I've attached a photo of the back of the case that the 321 was in when I bought it from Tourneau. Also, since the slope sides of the case, which I assume came from a polishing, just never looked right to me, I had the watch put into a 145/345.808 case that I had purchased from that NZ supplier on eBay back when the cases were going for around $500. I wasn't a very informed Speedmaster buyer when I initially purchased the watch, I saw it in a window and got hooked and went into the store...at least I had enough sense to have them take off the case back and show me that there really was a 321 inside. At this point, the watch is due for an overhaul, and I'm not sure that I want to leave it in the display case. I've started looking for a 145.012 case, but it looks like that's a bit of a challenge. Thanks again for the help.

a 321.105012.66 doesnt necessarily mean a 321.105012.66 cb case with sharp faceted and flat-footed lugs.

With the serial number on this movement,

is it best referred to as originally being a 145.012 from 1967?

the caseback might not belong to that watch. i suspect it is 145.012 from 67. i might be wrong.