Gotta pass this on - hopefully it will help someone out. I had a return line quick-connector seeping ATF out on my my AW4 tranny cooler, so I ordered a couple of aftermarket repair kits as pictured below because I couldn't find any of the original Mopar kits for the 3/8" line. The aftermarket kit comes with a plastic snap connector, O-rings, spacer, and "installation" tool. Luckily I ordered two, based on past experience with this junk. Sure enough, plugging it in using the tool into the tranny line female connector housing, and as endorsed by the FSM, it wouldn't snap in to the hard line, and I ended up breaking the el-cheapo aftermarket plastic snap connector.
Using the spare connector, I reversed the procedure by manually assembling the snap connector, O-rings and spacer on the male hard line vs. the female connector, and it plugged right in and snapped shut - no leaks.
Morale of this story? The aftermarket connectors are junk. The snap piece is fragile black plastic. On the OEM connectors it's white nylon, and much sturdier and flexible. I will replace the junk connector as soon as I can find some NOS original repair kits.