5k was in liteace vans and some jap spec corolla panel van. No 5k was available in the Starlet.
I believe they were mainly available in Japan, and were very rare in other markets.
As for the gaskets, they should be identical to the 3k and 4k gaskets. I can't confirm that first hand but apparently all the k series manifolds are interchangable so the gaskets should be the same.