.....don't think that is possible with the X frame tunnel, the angle and just no room for up / down travell of a one piece shaft. Just used a quality center bearing part and there should be no need to touch it for a long time.

Unfortunately, there's no really good way of putting a one piece shaft in the X frame cars.

You can do it by cutting some of the X part of the frame away, but you hate to do that to a classic car.

You can restrict the travel of the rear axle by using shocks from a 55 to 57 Chevy. Then you can fit a one piece shaft in, but it has to be a smaller diameter than you'd normally use.
I think 3" or "maybe" 3 1/4" might fit but for a shaft that long I think the recommended diameter would be more like 3 1/2" or more. (the "critical speed" of a 3" shaft that long is about 5,300 rpm)

It's also hard to install a one piece shaft on these cars. You usually have to disconnect the shocks and drop the rear end down to get it in.

So, it can be done but there's no easy way to make it work.

If you ever want to upgrade to a stronger two piece shaft, Inland Empire Drivetrain makes replacement driveshafts. They have one that's a little stronger than the factory driveshaft and they make another model that's practically unbreakable.

Thanks for all your input......I'm going to stay with stock....It will be fine for my use of the car.