More details of nominees on the SFWA 1975 Nebula Awards page.
Fritz Leiber Catch that Zeppelin!
Winner Best Short Story
Joe Haldeman End Game
Roger Zelazny Home is the Hangman
Winner Best Novella
P J Plauger Child of All Ages
Harlan Ellison Shatterday
Tom Reamy San Diego Lightfoot Sue
Winner Best Novelette
Time Deer Craig Strete