[njsteve]

The driver's side snorkel on any Pontiac 4bbl air cleaner from late 60s to 72 is the one you need to replace either of the snorkels on a 70 to 72 Trans Am air cleaner. Unfortunately you need two of them. (Even though both sides have the Thermac valve, the passenger's side snorkel usually doesn't have the heat riser tube mount on the bottom, but sometimes you get lucky). In these photos you can see the 4 bbl donor air cleaner, the flange area and the underside which shows the passenger side snorkel without the tube mount. This would be a similar process for any GM air cleaner. KevinW seems to be the expert on donor snorkels for Chevy stuff. He knows which are the right ones for the cowl air cleaners, especially the rarer automatic equipped ones that had the Thermac heat riser.