I noticed in my Haynes repair manual that in chapter 1 (Routine Maintenance), “brake caliper mounting bolts” torque spec is given as 26 Ft-lbs, but in chapter 9 (Brakes), “brake caliper bolt” is given as 84 Ft-lbs (66 Ft-lbs for the rear), which seems more appropriate and is what I went with. I’m curious if the 26 Ft-lbs is an error, or are they referring to something else?

There is no shortage of errors in the Haynes books. Which his not to say there is not also a lot of good information.
One of the more notable torque value errors is for the W123 motor mount bolts. It looks like they converted from Nm to ft/lbs by doing the arithmetic backwards. As a result, a lot of folks have stripped the threads in their motor mount arms.

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When cryptography is outlawed, bayl bhgynjf jvyy unir cevinpl.

The front 115 Nm and the rear 90Nm Source paper Mercedes Service Manual

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84 300D, 82 Volvo 244Gl Diesel

In the Auto Trade that brand of manual is called : "H.B.O.L." although as stated is still has plenty of good information in it .

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-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better