One more car based on GAZ 21 was a GAZ 23 developed for KGB and other special services, such as cortege cars. This version, also resting on third series car, had a 5,53-liter 195hp engine (a modified GAZ 13 Chaika unit) and automatic transmission. For better weight distribution such cars carried an additional load in a trunk. From the outside it was made to look like a standard GAZ 21.

GAZ 23 - basic modification,
GAZ 23A - prototype with a manual transmission,
GAZ 23A1 - with special equipment,
GAZ 23B (23Б) - lux modification.

Through 1962-1970 about 600 such cars were assembled.

Pictures can be found here:
ГАЗ-23 Волга