420A vs 4G63

what is the difference between the 4G63 and 420A motors, and how do you tell which one u have?
Is there markings? I have a 95 Eclipse GS and want to start looking @ some turbo's and some sites keep on talking about all these different motors; any suggestions are welcome.

Thanks,
David

You know which one you have by what car you have. Your car is a 420. That info should be in the faq sticky. As far as the differences the 4g63 is obviously built with stronger internals ready for boost. But the 420 is a bedplate design which should prove to be very strong with appropriate internals used.