Hey;
Was looking at a local shop that carries motors and trannys and did a search for 95-99 eclipse. The results came up with a 4g63, and a A588. What the hell is that? Here is the site: http://www.soshinusa.com/ This is exactly what it says:

Product Type: Engine
Transmission Type: N/A
Manufacturer: MITSUBISHI
Model: ECLIPSE
Year: 1995 - 1999
Description: 2.0 DOHC ENGINE
Engine Displacement: 2.0 L
Engine Name: A588

typo?

Might be some "manufacturer code" or something like that, I've NEVER heard of that number before.

I think it basically means the 420, some sites I've looks up gave me a funky engine code like that too.

I know I'm a few days late, but that's the Chrysler engine designation... I b/l the engine (even in Eclipses) has that written somewhere... check the firewall, my plate actually said A588...
it's the 420A (Mitsu designation)... same motor, just make sure it's setup for the Eclipses and not the Neons (I can't exactly recall, but the heads are transverse or something in the neons)