A-body shaft for Power Steering is 36.375 and Manual is 40.375. I had both at one time as I was converting Manual to Power. This is end to end of the shaft only, no splined steering coupler, and no broken pins on either to allow them to telescope. My searches here yielded the same dimensions.
For reference, the B-Body shaft for Power Steering is 41.50 and Manual is 44.50.