Master Cylinder, I can't find the right one!

[jamesd]

I have a 2005 Aveo Hatchback LS / Automatic without ABS. For the life of me I can't find a master cylinder for it. I check Autozone and Orilley and they both have it in stock but none matches my car. By that I mean the 2 larger ports on the bottom of the MC won't fit the adapter fittings off the original. The opening on the MC is smaller than the fitting on the car. I even tried a manufactured MC with the same results. The counter guys are baffled by this because the reman has the same stamp and number as the original. Has anyone ran across this?? I checked with my dealer and this part has been discontinued from GM. The GM part number they came up with is 93742291. Even the dealer used this part number with Orielly and had the same problem. The larger ports on the MC were smaller than the fittings. I wonder if the MC had been replaced before with a different model year? Any help on this would be greatly appreciated.