As to the original question, I would never replace the 70 amp alternator with a 70 amp alternator. They are POS. The difference between the 70 and the 80 amp is that the 70 puts out about 20 amps at idle whereas the 80 puts out about 60 amps at idle. The difference is more like as if you replaced the 70 with a 210 as the most important time has the 80amp tripling the current output.

This matters because the original alternator is the continuous source of battery problems in cars that use the AC and idle a lot. At idle with the AC and fans on the 70amp alternator is about 20 amps in the hole.

The other miracle is that the 80 amp costs me less than the 70 (only a couple bucks...BUT!). One will have to replace the harness MB # 124 543 45 26. It costs $57 list from MB and is simple to replace as it just goes from the alternator to the connector close to the battery.

WE now convert the old harness but this should only be done with suitable connectors soldered in place. A couple yellow crimp-on connectors IS NOT SUITABLE.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician