I am not sure how Bill got that manifold approved for the 273. It was probably some obscure memo or something in the parts book. You would not want the LD4B on a 340 You would want the LD340 which was a copy of the cast iron 340 manifold. I remember when most of the 340 SS cars used that manifold.
Glad you said that, I had the two confused. I was just thinking of the weight savings on the front end.
