For those who are interested, from AIRCRAFT SPECIFICATION NO. A-718
"S/N 4501 and up designated model 415-CD identical to model 415-C except for revised throttle and trim control, wide trim tab (1-3/8 in. chord) in accordance Erco dwg. 415-22031, improved fuel venting system, revised nose gear oleo strut, improved interior trim and installation of stainless steel upper fuselage skin."
