Mystery Drain Pipe - how to connect?

I'm in Phoenix, Arizona and my house was built by my grandparents in the 1940's. (This means that I know to expect pretty much anything when performing household repairs!) I'm replacing the cast iron drain pipe from my washing machine that connects to an existing underground drain that I thought was 4" ABS. (There was a reducing collar connected to the 2" pipe from the house.) Upon attempting to fit a new reducer fitting, I discovered that the 4" fitting was much too large to fit the pipe. I measured the part of the pipe that I cut off to make the new connection, and it had an ID of 3 3/4" and an OD of 4 1/4"! Is this some obsolete size of ABS pipe, or is it ABS pipe that has shrunk over the years, or is it not ABS at all? It seems a bit lighter and more brittle than new ABS. I don't know exactly how old it is, but it's at least 20 years old, if not 40. I guess what I really need to know is how I can join my 2" abs drain from the house to this oddly sized pipe. Thanks for any help you can provide.

Well, as it turns out, I found the solution to my problem last night at my local Ace hardware store. I was browsing their selection of ABS fittings when I discovered a thin-walled sleeve that was described as some kind of 4" adapter. I had a section of my old pipe with me, and the sleeve fit perfectly on it and increased the OD of the pipe to 4". I asked an employee if he knew the name of the pipe for which the adapter was made, but he didn't. I guess it could be the S&D PVC mentioned. Is S&D dark gray in color? Anyway, now I know at least what I need to do to work with it. Thanks for your help.