Thanks Eagle, that was what is was thinking off. Have made some measurements of the D35/10x1 3/4 backing plate and drums and the offset looked ok.
The reason I need changing is my original backing plates are all rusted out and new costs a fortune. A friend bought new ones and they cost him $193 each ( special order from US ),
and I have collected a few D35 over the years for cheap money, some broken but with good brakes.
You are lucky in USA to have cheap parts and a lot of junk yards with cheap stuff. Here in Sweden a D30 front axel without drive shafts and knuckels cost $ 200-400 and drivshafts about $ 150 each, if you can find
a j.y. that have any. Used front brake calipers $ 80-150 each and so on.
But I will newer give up on my american cars, have been driving them for 40+ years now.