Who cares about the battery? The diesels have used the 900-1000CCA batteries since the 70s and have as small as 50A alternators. You're focusing on all the wrong issues. You seem to know what you want whether its warranted or not, so let us know how it turns out.

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Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)