OK.. I left my driveshaft in the 'derusting chamber'..
. for a couple hours more than a day. Since the temp has been around 60 daytime and 35-45 at night, I thought a bit longer would be OK. What I found when I removed the driveshaft from the tube was a totally cleaned, almost 'blackened' driveshaft with paint stripes showing; orange and white adjacent and then a bit apart was a yellow splash. I should have photographed it before running water over it.. as when I did (even without any force) the orange/white paint began to run .. so I stopped with the 'washing' and took the first photo.
I stopped washing down and resorting to 'wiping only the unpainted areas with a wet cloth'.. then dried using an old hair dryer I then applied a lite coating of 'Metal Rescue -Stop Rust' over the painted areas. last photo. I don't plan to repaint the stripes; I'm thinking enough of the original strips will be visible to show originality on my unrestored car. I will apply Boeshield (when I find my supply)..
to preserve it as much as possible.
I measured from center to center of the driveshaft mounting rings and got 49-5/8" as closely as I could read it.