In addition to the failure of the spacer that sits under the idler gear (which I had made by turning down an extra of the spacer that goes under the speedo drive gear on the output shaft, too thin of a wall and not hardened, lesson learned), half of the bolts going into the adapter had striped their time-serts that I installed in July. Several felt sketchy when being torqed. They all clicked the torque wrench but just didn't feel right, I went ahead and ran it anyways. I attribute this to the Time-serts being to shallow of a thread depth. They were only about 1/2" long. My reasoning for not drilling deeper before was not wanting to remove the adapter from the doubler. This bit me.
So now I get to do it right.
Lets make this so it's never a problem again, ever.
Adapter gets removed and put on the mill. All holes and time-serts get drilled and tapped to 9/16-18 threads, and all as deep as possible. The lower two holes are drilled and tapped completely through the plate. So we're back to aluminum threads, but with fine pitch instead of coarse and with much deeper thread depth in several holes.
The lowest holes looks wallowed out because it is. This hole was previouly tapped, I drilled it out to and used a steel jam nut inside now. By wallowing out the hole I was able to get a SHCS inside to replace the stud on the 203 face which gives me the clearance for the 9/16 jam nut.
Bolt size comparison.
Next up, ruin more Toyota parts. Get lazy a just use a drill instead of setting it up on the mill.