Gentlement, it's a very nice work.
But could I ask (suggest) You one small thing? (Both of You, Ukraineball to slightly lesser, Orionfield to slightly larger extent)
To make Your "white" less white, as for now it's hard to notice any shading, panel lines etc. And to decide (Ukraineball) on ONE kind of "white" (DC-9 N760NC versus all others
Especially on DC-8 up to certain point difference between "lighter" and "basic" shades of white is almost nonexistent, and then becomes relatively excessive (in fact, in some places the "darker" shade at some point is darker shade of "white" and in some is the same shade as used for grey stripe along the bottom of fuselage).