Dave, the J9613-12 that Mark specs are correct. Attached is a pic of how they look. The centre steel bushing is bonded inside a rubber casing with some sort of fluid/gel inside. Bolt size for these using an Avi-pro mount is AN7-34.
This build the customer specifically asked for aluminum sheet on the seats, was afraid of damaging the fabric when putting stuff under the seat or in baggage area, and we also had heated seats. Had to add middle supports for the rear seat as well.
I usually cover the seats in heavy weight...
My frame's were 3/4" wide x .032 and covers were .025. I temporarily tape the frames to some tubing then after shrinking glue them to the fabric. The covers are one piece with a slot that slides over the tube. This leaves an opening behind the tube, but I covered it with a small piece of stick...
I guess I should have just asked here first, oh well. Thought I would post in case anyone else was thinking the same.
I have used the Casper Labs angled spin on adapter a few times before and really like it for cleaner oil changes and thought it would fit from my preliminary guestimate before...