It depends on if it is an eight day or a one day cuckoo. If you have approx. 60 links of chain per foot or more it is probably a one day cuckoo. Approx. 50 links/ft. or less make it an 8 day. 320 to 375 grams for one day and 1350 to 1750 for 8 day. Your best bet is to look on the back of the movement and write down the manufacturer and any numbers you find. Then contact a clock parts supplier with that information.
Stevens Clocks, October 2009
