Hi Cyril,
For the most part, the SAS wore US ERDL uniforms.
You may want to check out Osprey's Vietnam ANZACs Australian and New Zealand Troops in Vietnam 1962-72 by Kevin Lyles. Elite #103.
In the book Mr. Lyles writes, "Though a small number of indigenous 'tiger-stripe' uniforms were worn, the US ERDL Camouflage Tropical Combat Uniform quickly emerged as standard SASR operational dress in Vietnam."
-Sherb