https://www.google.com/url?q=https://github.com/Ultimaker/UltimakerOriginal&usd=2&usg=ALhdy2-gScf2sRfaM_4cIiizvwEP67QxTQ
Z lead nut drawings should find from um original github website. I don't remember it correct name there but... If I remember right there was different z lead nut at um original plus.