Here are the pics of one of the frame to sill clamps. There are at least three different clamp used, they are all in the TM. This is an example of the 'tapped plate' kind. That means that one end is threaded for the clamping rods and the other is simply drilled for split washers and nuts.
Here is the clamp. The bolts are on the frame side. The tapped plate is against the wood. I cut the plate at the top with a grinder because I did not want to disturb the length of the clap. Pretty smart of me.
This is yeager. He went out with me to CA to get the bed. His technical ability is somewhat lacking, but he fetches a mean tennis ball.
Here's the money shot. I measured 14 7/8th or 15 1/8ths depending on how you want to call it. You must subtract the width of the bottom plate (5/8ths) because I was measuring from the bottom of of the bottom plate to the bottom of the top plate (I had the hook on the end of the tape measure over the plate. The plate is 5/8ths inch. I honestly don't think it matters. You have so many other bolt holes that have to line up (cross sill to frame supports) plus however your wood is acting that day (moisture content) that I would install the bed, shim it with scrap and one you have pins/bolts in the other holes then make your measurement.