J.H.
The head gasket you buy here on Fastlane is the exact one you'll get at any MB dealer: Elring. If you do the job right, there's no reason why this gasket should leak for at least 100k, unless of course you overheat the car
If you have any Q's, email me. About half way into this DIY, you'll ask yourself, why in the hell did I attempt this#@#% Once you're done though you'll feel a great sense of accomplishment. Take your time, and don't make any stupid mistakes that will set you back.
Good luck!
~Paul
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'91 300E, 215K miles