Here's the measurements I took on the rear seat of my 6169:
The lower seat cushion:
Width across the seat...63 inches. Height of seat where a passenger would put his feet...11 1/2 inches. Height of seat at center of cushion where the driveshaft hump is located...8 1/2 inches. Depth of seat from front edge to where the seat back cushion meets the seat...18 inches.
The back cushions: Width across the bottom edge...63 inches. Width across the top edge...57 inches. Height (from top of seat cushion to top of back cushion...23 inches. Center fold-down arm width...6 inches. Height of center arm when in the "down" position...5 inches. This would also be the depth of the back cushion. The back cushion is made up of three parts with the arm rest being one of the parts and is full length, meaning it goes from the lower seat cushion to the window package tray.
I hope this helps. Good luck with your project. Russ Hobden #1235