Juno I was a four-stage American booster rocket which launched America's first satellite, Explorer 1, in 1958. Juno I launched 6-times with 3 successful deploy of Explorer satellites. Juno I concised of a Redstone first stage, 11 Baby Sergeant cluster as a second stage, 3 Baby Sergeant cluster as a third stage and 1 Baby Sergeant as a fouth stage (part of an Explorer satellite). The vehicle launched from Launch Complex 5 and 26A at Cape Canaveral Air Force Station.
I recommend turning on "Advanced tweakables" in KSP settings.
Here are my other projects.
Juno I
Explorer satellite