I may be seeing it wrong in your pic but, Yours looks solid across the top to me. Mine only has an inch and a half on each end with a five inch gap in between. If I cut the hole the same size as on my DT1, I'd have something that looks like this. Which doesn't seem like enough to hold the weight I'd like it to hold.
Edit; Went back and looked at your pics again. After looking again, I can see the carry handle hole. Did you cut your load lifter holes right at the top seam?
I cut the holes directly across the seams about two finger widths down from lid seam. I slid the pack onto the frame and marked them with a pencil then made cuts.
Sorry for necroposting, but this is very close what i'm looking to try to do. I want to attach a "NICE" 6500 or 7500 to a duplex frame. Can you guys show more detail on how you got the whole thing attached, I understand the top flap piece with the load lifters.... I'd like to see some close ups of the rest of the attachments, and did you guys need any extra buckles or straps to make it work?
Has anyone tried mating the duplex with any of the bigger Mystery Ranch pack bags?
Thanks guys.