We supplied our automotive customer slightly over 1,000 pieces of these large custom aluminum standoffs using 6061 aluminum material with plain finish.  The diameter was .75" and we ran two separate lengths: 4.75" and 5.125".  The female/female thread on both lengths was 1/4-20 with minimum thread depth of .50".  No PPAPs were required for these specific parts and only material certs and a certificate of conformance was available.