Sorry Dennis, yours was the only reasonable reply, and I accidentally deleted yours at the same time as the others
OK, the posts I deleted all complained about your apparent lack of understanding about things that most of us probably take for granted. So let me kinda hit on a couple points here and let you take it from there.
Our cars have two-piece driveshafts, yes. Same as the 240SX (S13 and S14, only not the front section is shorter on those). If your car came with a 1-piece shaft, then you will need to keep this in mind later if you decide to do a swap. For now, its no big deal.
Now... about the tire sizes... tire sizes, and wheel sizes, have absolutely NOTHING to do with the driveshaft setup. The driveshaft doesn't care what wheels or tires it is turning in the back, nor what is on the front.
That said, let me explain something about tire sizes and why your car has them different on front than on back.
"215" or "195" is the width of the tire, in millimeters (mm). So the 215's are WIDER than the 195's. Putting the wider tires on the back, and the narrower ones on the front, gives you more traction in the rear (which are the wheels that drive the car), and better turning in the front. This is what's known as "staggered sizes" or just "staggering"... wider on the rear than the front. You can do it with tires, on a set of four wheels that are all the same size, or you can do it to the wheels as well, such as a 15x7" pair of wheels on the front, and a 15x8" pair of wheels on the rear.
Anyways... you want to keep the 215's on the REAR where you need traction the most. But not everyone has staggered widths, many people just run the same size on all four corners.
If you want to ask more questions, don't let people discourage you from doing so. Everyone has to start somewhere.