What if, in the early 1970s, NASA painted themselves into a corner by insisting on the most outrageously expensive version of the Shuttle they had, refusing to accept the reality of post-Apollo budget cuts, and ended up stuck with a capsule-based launch system, leading to the construction of a Mir-style space station. Little changes ITTL, except for the fact that Jimmy Carter taps John Glenn as his running mate, and a few states in 1976 and 1980 get switched around, but not enough to change the outcomes of either elections. Then, in 1984 space becomes a bigger issue because a former astronaut is the Democratic nominee (Gary Hart still can't keep it in his pants) so in the 1985 State of the Union, President Reagan announces that he will order NASA to revisit the idea of a Space Shuttle, with a deadline of 1995.
What is the Space Station like? What effect does an extra 15-20 years of technological advance have on the new and improved Space Shuttle? Do the Soviets do better in space because they don't feel compelled to play catch-up with Buran? Does this later Space Shuttle do better without the DoD breathing down NASA's necks since they'd have had to learn to live without the shuttle too? What might they call the new shuttles ITTL? (personally between Star Wars and the calendar, I'm betting on a Space Shuttle Millennium)