Yep. Most likely an Allis Chalmers model G. However, there was another company that built a knock-off of the G ... unfortunately I don't remember that company's name. These were built from 1948 through 1955 and, if it is an AC G, you can find the serial number on top of transmission case to the rear of the shift lever.
These were very versatile tractors and, as has already been mentioned, were very popular with produce farmers and larger home gardens. Nearly all of the implements designed for the AC G were belly-mounted. This configuration provided the operator with an excellent view of the belly-mounted cultivators that used to be used for weed control. Also, the G had a single-bottom plow that was belly mounted ... again a very unusual configuration.
These old AC Gs are not rare so the value isn't too high, but they remain a nice collectible tractor. The orange paint color in the second photo appears to be too red to be accurate, but is still looks nice!