Mine is equiped with AC. Blower fan motor is

Mine is equiped with AC. Blower fan motor is burned out. Every part store I have checked with says they have two available, I orderd one. Mine has a plastic housing which can be removed, and then taken apart in halves so you can replace the motor after removing the squirel cage fan. Well the new motor did not work because it had a flat top. The old one was tapered near the top becasue the plastic squirel cage fan has a cone in the center. The tapered top allows for the fan to mount. The flat top motor that evey part store says will work does not allow for this. Chevy/GM doesnot mfg the part anymore but they say they can get an origanal part for about $300. I think this is a bit steep considring the value of the car. Every part store seems to carry another version of the motor that appears to have a flat top and a built in metal flange which appears to take the palce of the plastic one I have. It may work if the part above the flange is not too high and the shaft is high enough. But who can tell from a picture? Does anyone has experience with this problem and how did they overcome it?