My '53 Model had plunger columns with what looked like a finish similar to the fork legs, which I do not think were hard chromed. Both parts had some kind of plated finish, the same as on gearbox layshafts and mainshafts. These always look too good to be just plain unfinished machined steel. Maybe they are hard chromed?
My plunger columns had wear to this finish, so in true penny pinching style, simply cut another notch on the other side of the columns to match the pinch bolts and turned them round so the worn areas were on the non-load side. Sliders had bronze bushes top and bottom, and space between them for lots of lovely grease. ( Early models, grease nipples stick out, later models they point to the rear).
It was a long time ago......at a time when even pattern parts were rare and expensive.
Some Hard Chromed Steel tube should do the job if you want to make your own. From memory it's 1" OD Tube.
For all the marketing mens' enthusiasm, the Plunger system is at best flawed, and as long as the back wheel doesn't dance enough to scare you, don't worry. The sliders should be a nice sliding fit, with no chatter, slop or rattle. Damping is down to the mixture of grease & dirt that accumulates and the inevitable less than perfect alignment of the rear frame section and its plunger columns.
Better to substitute a steel tube for the top spring and make a Rigid Plunger. More predictable handling, so they say.
Swarfy.
