Has anyone replaced their main battery with an aftermarket battery and what was your experience. My car calls for a A 000 982 21 08 it has 12v 80 ah 800 A. I'm looking at an Everlast from AutoZone That looks exactly like the MB one.

Everlast is Walmart's brand. Duralast is Autozone's brand. Maybe they're the same battery made in the same factory -- who knows?

I replaced my G550's MB branded OE battery when it died after 42 months with an Autozone Duralast Platinum H8. It's been fine for 21 months.

MB use Varta AGM

As long as it is the same size and has at least the same crank amps or better and it is a AGM battery you should be fine. Direct swap no biggie.