6/8.5 on 1980 dually...and then some

Are those the airlift load lifter 5000 bags? That's the kit I want to order but summit says it won't work since its lowered 8 inches in back. They said there is not enough room for the bag to fit in there and work properly. But if that's them then obviously they are wrong.

Umm I'm not sure I got them from the sport truck direct I was thinking it was more like the 2000. Series but I could be wrong