O-ring for Andair Gascolator
As an update, the Andair 375 gascolator uses a 2mm x 39mm(outside diameter) 75 Viton black o-ring. I could not find any available from aviation vendors so I tried McMaster Carr. They carry a 75 Viton black 2mm x 35(inside diameter) which is the same as the 2mm x 39(outside diameter). They come in a pack of 10 for $16.50 plus tax and shipping.
I applied a very thin layer of silicon grease on the o-ring and put it on the gascolator bowl. It was the perfect size and assembled very easily with the gascolator body. I pressure tested with the boost pump and it did not leak.