On an 1983 E350 from the FORD shop manual says the range of torque is 175-260 and the nominal torque is 220 ft-lbs of torque.
I always used 220 FT-LBS and had no problem with the 8 lug nuts for the 15 years I had the class "C".
I even bough a 3/4" drive torque wrench for the the lug nuts.
The newer Fords like my 1994 F53 had a lot less torque (140 FT-LBS) for the 10 wheel nuts.
Ford had a problem in 80's with the nuts coming loose.
I would not trust a Chiltons manual on this if it says something different.
From the 1983 FORD Shop Manual were the Chiltons manual gets its information from:
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