From a bit of reading the 454 movement is a family of movements, the 451 movement is the same mechanically just the amount of jewels is different, I believe that particular part of yours that's broken is part 1175, searching online you can find 451 movements in various states of disassembly for not much money so it might be worth starting there.
She was, stood there sighing as I took a few pics to the get the lighting on the dial right, she's used to it!
Timex had a long running relationship with Dewalt, they produced both the original 80's/early 90's Ironman in a Dewalt variant as well as an Atlantis and this later 90's/00's variant, it is a tool watch after all!
My SRPD76K1, crown isn't screw down which irks me a little and it's quite ostentatious but otherwise great watch, good timekeeping and good lume.
Pretty sure, they were sold pretty much directly to competitors doing the Ironman which needless to say isn't for kids, I don't know why kids would need a split second timer and chronograph function