They may be different, BUT...
Without one of the blue handles to measure, I found the older yellow handles to measure this way:
Outer "cheek" diameter = ~5"; estimated inner diameter ~ 4"; width between faces ~1".
"Tube" diameter: VERY close to 0.875" (7/8.")
IF you can find PVC tube 7/8" OD, it should fit.
The "tube" on the yellow pieces had a slit about 3/8" deep, and a slight raised ring at their ends. This allowed the tube to be definitely 'stopped' from pulling through the reel, but capable of removal when the slit was squeezed firmly.
A cotter pin through one end should limit the tube from pulling through, and the hand's grip on the other face should keep things happy.
You're welcome: \LOU