I took delivery of my 1987 300E on January 8,1988 and as it was new it had a M/B Battery. My records showed it lasted until September 9,1993 and was replaced by an InterState MB88. This batery lasted until, the reciept is in the glove compartment, 1998; this battery was defective and replaced after 5 years service, no charge year 2000. This tells me both batteries are good if taken care of. Price shop, but don't include the Diehard battery. I hope I have the dates right. Happy Trails Beep Beep from Houston.
expensive ain't always the best.