I'll have to look it up for dates, I don't know, or how widespread by then. I think there was a later post-original-production modification needed to the back cargo door/hatch for airdrops and maybe the zipline, but I don't know any of the specifics off-hand.
Thanks! I love the older planes and aviation and love volunteering at a local museum, which conveniently has a Commando parked on its ramp (hasn't flown in a couple years, some AD out on the props - something like 10-20grand a blade to fix, three blades a prop, two props..... anywhoot). I'm gonna try to remember and ask if they're going to fire her up and run the engines anytime soon the next time I go, it's 'bout the only thing exciting that gets to happen with her these days.
That reminds me, big antique birds and all, a couple weeks ago they flew out the Lockheed Constellation here at Camarillo Airport to Chino (one of the museums out there purchased it) and I got some amateure footage of it that I never took off my camera yet, (probabley the last time one will ever fly, lord knows).