Strangely it's the other way around. Standard 88" rear springs have 11 leaves. Standard 109" commercial rears have 8 leaves which are thicker than the SWB leaves, but station wagons have 8 normal leaves and 2 helpers (the helpers are very chunky). 109" 8+2 springs work nicely on my 88" IIA and I'd guess they would work well on lightly loaded 109" commercials too. I'm not 100% sure that the 109" commercials are 8 leaf, I'm just assuming that because it's what I've got on my 109", but I suppose I could have the heavy duty type fitted to 1 ton 109s.