Here is a patch which converts the mapper in Darkwing Duck from MMC1 to MMC3.
Darkwing Duck (USA).nes - NOINTRO
CRC32: 307D0FC4
MD5: 459837F4E8FCBAF29BD66ED926B6882E
SHA-1: 7188D8CE3D8D2A0DCD7B10FBC23A6F84FA9C4161
SHA-256: B7FFF97F34D7142765685C6505AD54285CFD7E847E6943BC53E432C4F25FA49C