Perhaps I can help with some of the confusion on the J model rollers.
The RAAF C130J's as you know are stretched.
Are so I believe are most of the RAF ones.
When the aircraft were in production at least, there was no flip over roller developed for the stretched J models. Neither the RAAF or RAF were prepared to pay the high developement costs.
End result was at build time (it may have now changed) no flip over rollers for stretched J's. However on standard length airframes the flip over rollers were available.
The RAAF apparently cooled off on flip over rollers, as experience with other aircraft (the C141 mainly) indicated they could be a high maintenace item because of dirt and sand.
However this appears to fly in the eye of the C17 experience, where their rollers appear to give little trouble.
Regards
Col Tigwell