I am working on a couple of G80 rigid frame projects. Mostly 1949 G80C, but partly bitsa. I will admit that I am not experienced with rigid models so I am needing some questions answered by those more knowledgeable. I have several petrol tanks that have the seat nose area filled in (see pictures) and I have been told that these are for the rigid models. Is that correct? If so, how does the saddle mount as the tank will cover up the saddle mount pivot hole through the frame.
Also, I am confused on the changes in rigid frames over the 1948, 1949 and 1950 years. Will a rear frame section from a 1948 not work with a 1949 or 1950 front frame section? It is my understanding that the geometry changed in 1949 for the front frame section and the wheelbase was lengthened. Is that correct?
Thank you.
![Image](https://imagehost.vendio.com/preview/ro/rocket52/1951MatchlessRigidTank1.jpg)
![Image](https://imagehost.vendio.com/preview/ro/rocket52/1951MatchlessSAtank.jpg)