the "E" is very much under the cosh
True the "E" has been anything but well but is not barred! Mrs"E" has me very much terrified about being given the elbow if I don't hang up the goggles and silk scarf.
However the DC10 does have an Oswald efficiency factor of about 0.83
Fundamentals of Flight by Richard Shevell, published in 1989 is still in print. ISBN: 0133390608
Very good on that era of jets, the DC9 and DC10 being particularly well examined, Shevell being at the forefront of Douglas design at the time.
With regard to aspect ratio efficiency there are many factors including slenderness ratio, wing sweep, airfoil section. "e" may not be a fashionable notion but there are certain models and marques flying and proposed that would deserve a factor of 0.93 if the flight dynamics were explained in the lore and lingo of earlier times.
A famous engineer once heard that the topic he was now expected to mastermind was "quite simple really". His reply? "Don't worry I'll soon complicate it!" The notion of "e" was very good in its day when tables and graphs of all sorts of parameters were used to initially guesstimate upper and lower bounds of performance. I think you'll be okay with 0.83 for the DC10 but don't try to extrapolate from Shevells work when it comes to Company "A" and Company "B" products as currently offered. Wing design has moved on heaps.
Best Regards
the "E"