I tried searching on here for it for some other stuff, but to no avail (Probably wrong keywords), but for those who want to know, I found it eventually.
Hyundai Engine Code and Their Mitsubishi Equivalent
Hyundai built its own engine, based on engine blueprints they bought from Mitsubishi.
Here are the engine code equivalence, left side is Hyundai code, in the right is the Mitsubishi engine code.
Hyundai code G4DJ = Mitsubishi code 4G15
Hyundai code G4CR = Mitsubishi code 4G61
Hyundai code G4CP = Mitsubishi code 4g63
Hyundai code G4CS = Mitsubishi code 4G64
Hyundai code G4CN = Mitsubishi code 4G67
Hyundai code G6AT = Mitsubishi code 6G72.
List below are Hyundai's commercial vehicle name, with its engine name and equivalence with Mitsubishi engine code
92-95 Elantra 4g61 G4CR
93-95 Hyundai Elantra 4g67 G4CN
90-94 Hyundai Excel 4g15 G4DJ
89-91 Hyundai Sonata 4g64 G4CS
92-95 Hyundai Sonata 4g63 G4CP
89-93 Hyundai Sonata 6g72 G6AT
90-92 Hyundai Scoupe 4g15 G4DJ
Post was located at http://free-mitsubis...-and-their.html and was valid on Saturday 30 June 2012 at 2150h ACST (GMT +9.5)
Hopefully this can come in useful to others