I am assuming this is a USA forum, so I will ask- I have a water main feed tube/ pipe, black in color, feels exactly like HDPE, is 1 3/8" ID (1.375) and 1.900" OD., same as 1 1/2" iron pipe. It was installed in 1971/72 in Los Angeles County. I need to adapt to it to install a new water meter/ backflow valve, 1 1/2" in size. I do not want to dig up 500 feet of driveway to replace it. I could not find any reference to it as far as what it is. The closest I can get to a fitting is 2 different parts in the Ford catalogue. Any ideas what this is? Any and all suggestions are welcome. Thanks in advance.