50 hertz .. all 5xxx , 6xxx, 7xxx and 20xxx /21xx are 50 / 60 hertz. 100 hertz grundigs are 18xx series. i tested 2 72 cm 29 inch grundigs and didnt like em . a 29 inch philips would be a better choice concerning picture quality. tube is the same , but the philips chassis are much better . but i wont vote for 29 inch lowres anyway . for me its a nogo , even with the best tubes available. lowres on monstercrts is like neogeo on a 16:10 lcd .
cuc 4-7 are poti based , cuc 2xxx digital chassis types ( some with few , others without geometry potis , depending on the model)
for detailed list of ancient grundigs crt tvs u may google fitforfuture pdf.