The 105.012 is the first asymmetric case Speedmaster, and the first are marked -63 in the back and have a dial without T marks. This reference was produced at a similar time to the 105.003 until it was replaced by the 145.012 in about 1967. The 105.003 continued to be released by the factory until 1969.
Original pushers on this reference are 5mm wide and 3mm tall (Strictly speaking they are 2.7mm tall but very hard to measure in situ.) and are known as Short and Fat pushers, or mushroom pushers. The original ones have fat necks when compared to service replacements.
For me the shorter fatter pushers are very attractive and fit with the case perfectly, and I especially value the originals with the fat necks.
Below is a side by side comparison with the original pushers on the left hand case.
The dials come in all variations of T marks, that is none, close spaced or wide spaced.
All are fitted with white baton hands, and all Chrono hands observed have been drop-end.
This is the first reference to have the PROFESSIONAL word on the dial, also the first asymmetric case, and was produced alongside the 105.003 for all of its production.
This reference has such a wide variety of specifications, there are collectors who concentrate only on this reference with good reason.
This reference is unusual in that for the -66 there were two manufacturers for the case. See below in the -66 section.
The -63 also often caries the “symmetrical” clutch bridge, where as subsequent 105.012’s have the asymmetrical bridge that all later 321s carry.
Note as of September 2017: I have now seen a few 105.012-63 with an asymmetric bridge. I think I have to accept that either is correct. From a collectors point of view, the symmetric bridge is more interesting, but I would doubt it would affect the value.
2052 0xxx – 2052 1xxx
Very rare. The T’s are seen on all dials.
2052 7xxx – 2282 5xxx
2282 5xxx – 2452 7xxx
The -66 seems to me the mst common of this reference offered for sale, and commes in two case executions. The 105.012-66 sub reference has two case manufacturers. Huguenin Freres who also made the cases for the previous references, and Centrale Boites.
The CB cases differ in that there is a small line between the polishing planes on the lugs. All the -66 case backs have a single step.
Here is the close up details of the lug facet on the CB case.
Here again are the two different case types for comparison, first the HF case:
2453 xxxx-2544 xxxx