My mistake. For some reason, I thought everything was bolted up except this. Since its all loose and the C shackle isn't attached, maybe get a garage helper to wiggle the spring (shackle end) while you wiggle the bolt into its mount. It might be easier to get the springs mounted (since there's a chance of tolerances being off a bit), then attach the axle.
I'm guessing once it's all together and greased, it should work okay.
For peace of mind, with the axle out of the way, it will be easier to measure the criss cross distances in Section, R, FRAME. The back measurements are C-D (the spring mounts): 48.48"