[Paleo Conservative]

The most important difference is that it has a primary mirror 3 times the size of the Kuiper Airborne Observatory.

Which was about as big a telescope as could be fit in a C-141. Being the C-141 prototype, there were enough idiosyncracies in its configuration to make it not worthwhile to convert to the stretched C-141B configuration. It was one of just a handful of surviving C-141A's to not be converted back in the late 1970's early 1980's.

[shorty_harris]

Well, I don't think it was ever under consideration for this modification. It was under civilian ownership, and had already been heavily modified for it's mission with NASA. I used to work on this project, many years ago...

Sadly, that aircraft sits out in the weather at Moffett Field, CA. Most of the C-141's have been chopped up...I wonder if there are any more A models left?