Stock leaf springs on a 1970 Duster 318/340 - how many leafs?

I have a dilemma and need your help. How many leafs did a stock 318 or 340 Duster have? My 1970 Duster have 5 leafs, it was originally a slant 6 car and now has a 273. I cant pass inspection here in Sweden with 5 leafs, they say it should be 6 leafs. We're they even ever sold with that?

Could anyone point me to some literature that I can show to them to prove this?