Skypilot got the important stuff. Bulova rated them to 1-3 minutes variation/year which was phenomenal for this type watch at that time. They were only marketed from 1972-1977, with most I have seen being between '73 & '74 it seems. Compared to the 218, they were produced in far fewer quantities. There was even a 100th Anniv. cased Accuquartz - really rare! The 224 caliber is based on the 218 but with the important difference of the quartz module used as described by Skypilot. The tuning fork frequency is also slightly higher than the 218. Regulation is quite different from other Accutrons. The weights on the tuning fork are only adjusted to get the tuning fork synced with the quartz crystal. Actual time keeping is adjusted by a series of six tiny screws in a resister pack. The presence or absence of screw(s) and where in the line of six positions, regulates the watch. I have experimented on one of mine to increase its accuracy with some positive results buy still need to learn more. To me, the Accuquartz represents the pinnacle of bulova's Accutron development as they battled the flood of quartz movement watches being marketed by the competition. It is not a cheapened movement as is the 219, and usually sold for a higher price. You must be careful because, just like 218 & 219 cased calibers, a replacement quartz movement may have been installed by Bulova or a watchmaker when the original movement no longer functioned. If the watch is the Day/Date version, this can easily be detected because replacement quartz movements only had two letter Days, while all other Accutrons, except for the 230 caliber, had three letter Days. If the watch is Date only, or neither, then you can only tell be the jumping second hand or seeing the movement.
