I am standing on the hose...you want to know what tunics had been used before 1919?
Difficult, because Reichswehr used and altered nearly all of WW1 tunics in the first jears after the war due to the regulations of 1919 (this is why this tunic-type is called M1919): new collar and cambered cuffs instead of the WW1 cuffs, holes for the arm patches. All tunics also had to be altered to 8 button front. You may imagine that nearly no one cared about that as you can see on pictutes from the time...
My tunic I am talking about has the marking 139R referring to the saxonian IR 139 in Döbeln. I think it was a so called M 15 tunic or a simplified Feldrock-version of the model "M1910". Other markings of WW1 are missind so I think it did not see action in the great war.
All the other markings are from Reichswehr showing the year 1924 and 4th clothing set indicated by IIII and finally an "A" for "ausgesondert". This means that the tunic was abandoned from service in this year.