4G63: 2.0L- May or may not come turbocharged. Found in 1990-1999 Eclipse/ Talons/Lasers and 2003-2007 Evolutions. Also found in 1990-1992 Galant VR4.
4G64: 2.4L- Most commonly found in 1995-1999 Eclipse Spyder Non-turbos. Also found in other non-DSM platforms such as mid to late 90’s Galants, as well as in the Mitsubishi Mighty Max pickup.
420a: 2.0L- Found in 1995-1999 Eclipse/Talon Non-turbo FWD cars.
As far as problems, nothing really out of the ordinary except for crankwalk in the 95-99 model year 4G63 seven bolt. (The six bolt 4G63 in earlier model years didn’t have this problem.)