In order of age, oldest to youngest: Nos. 2, 1, 3.
I have three Piano 36s in near mint condition. Two are old with the white lettering, and one, which I purchased brand new some years ago, has gold lettering and has the “made in Germany” lettering on it.
In the case of all the Piano 36s made in Germany, any variability in playing, tone, and quality of construction I believe is just due to variability in manufacturing and materials over the years. All three of my Piano 36s sound and feel similar unless you really stand there and get obsessive about noticing difference. The black keys on my newer one with the gold trim wiggle more that the those on my older ones. The one liability of the older ones is the thinness of the mouthpiece fitting. Many of these that you see for sale have cracked mouthpiece fittings. Hohner recognized this problem and the newer ones have a much thicker wall. You can see this clearly in Bruno’s photos. Even being very careful with mine, I managed to crack and chip the wall of the mouthpiece on one instrument. I now mostly play the old ones without using a mouthpiece. When I do use a mouthpiece, I wrap the fitting with electrical tape about 5 or 6 time to reinforce it.