After finally getting a reply from Dutchmen, they ‘think’ it’s a Lippert (Venture) landing gear, they’re not completely sure since they were acquired by Keystone in 2014 and I guess their record keeping is shaky following the acquisition.
From what I can tell, the tabs on the existing installation seem to line up with what Ultra Fab recommends (13.5 inches between bottom of lower tab and bottom of upper tab), so I’m hoping this will be relatively straightforward.
Right now I’m out camping so I picked up some cinder blocks and a bottle jack to the frame to keep things stable. It’s a hillbilly solution but seems to work!