During the recent research my wife did in order to paint a South Vietnamese M8 Greyhound ("Mrs. History PhD strikes again!" - April 13, 2015), she came across an article that described several ARVN M113A1's that had been locally modified by adding turrets to them taken from non-operational M8's. She (and I) found this intriguing, though no amount of Googling since then has managed to turn up a period image. Undaunted, my wife has forged ahead and I have provided the necessary bits and pieces for her very first kit-bashing!!
M113A1's in South Vietnam, were they ARVN, US, or Australian, generally had the flat, rectangular trim vane (really just a breakwater) that you normally associate with the M113:
So here is Mrs. History PhD's offering:
She's really taken to the "severely grubby" look that I prefer. If you've never spent time around military vehicles that have been in the field for more than an hour or two, take my word for it, you really cannot overdo the muckiness. I bought the wife a bottle of Mig Productions Vietnam Earth pigment powder: