1977 900GTS air filters

I am refittihg the original air filters which came in a box when I bought this bike some years ago. It has had several previous owners and a number of alterations to original spec. have been made. The front filter fitting is obvious but although I can see roughly where the rear one should fit,there do not seem to be any attachment points/ brackets/ bolt holes etc. The various manuals do not give any details.
Any advice would be welcome. Peter

Are they they same as the darmah?
2 M6 bolts inside of the box fixes them to the frame.


Dear Kevin, Thanks for reply and photos. The brackets are missing - there are just some weld stubs left on the back of the tube which I would not have noticed without knowing where to look! I shall have to make some. Could you possibly let me know the dimensions i.e.the distance from the downtube centreline to the bolt holes and how much the brackets project from the front of the tube. They appear to be different. Peter

OK Pete, I’ll get some measurements.

Dear Kevin,
Thanks to your advice and photos I have now been able to fit the original air filters. This has been a longer job than I anticipated because, apart from having to make and fit the new brackets, a previous owner has fitted Rita ignition. That’s fine, but the amplifier was fitted where the front air filter box should go so there has been some juggling of electrical bits in a limited space and some rewiring.
Happily, all now seems OK. Best wishes, Peter Aldridge