My source data is available upon request, or you can read it at www.1911forum.com link

*The earliest Ithaca pistols were produced in early 1943 and shipped in non-sequential order.

*The serial number was originally stamped in a large Roman script type font. This font was used on approximately 250-275 pistols before being changed to a smaller, deeper font that was used throughout the rest of production (the 246th serial 856650 features a different font compared to the 278th serial 865682).

*Many of the earliest Ithaca pistols featured an I-stamped prefix to the serial number. Fewer than 246 were stamped this way. More serials are needed to further narrow down how many had the I prefix, the change happened somewhere between I-856531 (127th serial) and 856650 (246th serial).

*Ithaca was supplied with 7,000 unfinished new Colt M1911A1 frames and 2,200 Colt in late 1942, prior to their manufacturing of the pistol in 1943. These frames can be identified by the long frame extension/tang in the area of the grip safety, which was unique to Colt-manufactured M1911 and M1911A1 frames (books by Clawson, Meadows).
*I would like to make note that the above frames are separate and different from the 6,200 vintage surplus M1911 WWI Colt frames also supplied to Ithaca via Springfield Armory. The vintage WWI era frames are typically stamped with H & G by the disconnecter, and may feature the heart-shaped cutouts under the grip panels. On the WWI frames Ithaca removed Colt's external markings, and finished machining them to M1911A1 configuration by adding the finger grooves in the trigger area (books by Clawson, Meadows).

*Approximately the first 30,000-35,000 pistols were sandblasted and finished in Du-Lite blue, before being changed to a Parkerized finish somewhere around serial 890XXX

*Frames were serialized by Ithaca, inspected (typically the small FJA stamp early on), proofed (P and flaming bomb stamps), and accepted with crossed cannon ordnance stamp on the rear right side.

*Small parts such as the slide stop, mainspring housing, thumb safety, and hammer, were checkered during early production. They would be serrated later on.

*The flaming bomb stamp on the frame changed locations from behind the disconnector hole (856682 and prior) to the inside of the dust cover by the slide stop hole (somewhere between 856683 and 861698).

I finally took it home on Tuesday. I stripped the gun down and gave a quick soak in kroil overnight, then gently cleaned it with a soft toothbrush and reassembled the next morning. It looks to have been rarely fired, and only disassembled/reassembled a few times. I know it was taken apart at least once because of the idiot scratch which was on it when my friend bought it (he sent me pics while at the store buying it), and there are also a few scratches on the recoil spring guide rod from the spring being installed and removed. It's a shame the gun was stored in a holster, otherwise the finish would likely have held up better.

Of interesting note to me are the Rockwell Hardness testing points! These leave behind dot shaped marks approximately the size of a period. Rockwell hardness testing helps determine the strength of the metal, and whether heat treating has had the desired effect (when applicable).
The most obvious test point I found is located at the front of slide on the right hand side, 1/2" aft of the stirrup cut where it meets the dust cover taper. This is a common location for these marks.
There also appear to be a few hardness testing points on the frame, although some could be indexing marks from a tool during the manufacturing process.
*immediately below FJA stamp
*the top surface of the right hand side frame rail just before feed ramp