If you are an Amazon Prime member here is the housing you need and it even comes with a spare cable for $7.50 delivered. The housing is 66" long so be sure that's enough.

https://www.amazon.com/Shimano-Shift...le+shift+cable

I buy my shift and brake housing in 25" rolls and I'd be happy to send you what you need but I'm down to just enough shift housing to re-cable one bike.