Yep, it's a range. The whole idea is to provide a specific tension on the bolt. Ft-lb on the end translates into lb of tension in the "shaft" with a lot of geometry. Now throw in the variables: new vs. used (corroded) bolt, lube vs. no lube on thread, smoothness of clamping surface (friction), replace with original or somebodies "equivalent." The engineer either goes insane trying to predict it all or CYAs himself and gives a range for the variable extremes. Sounds stupid until you think of the kind of life a bolt can live - seaside or desert, hot or cold, maintained or left to corrode away, lots or just a few lawyers.

Clean and lube or lock(tite), then tighten to your best judgement.

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daBenz - 1970 220D