I took the first step in attaching my engine mount. 3/16 bolts are thread in from the inside and the mount is slid over them then snugged up. Next step is to remove each bolt and use the mount as a guide to drill the 3/8 bolts. I would have that done already..but it occured to me that I don't have those bolts yet. Aircraft Spruce will cure that problem....so I'll leave it bolted like this until they arrive....
