I'm looking at the picture of his drive shaft, and see there are several "clean" places on the yoke. That would indicate to me that drive haft often runs much farther inside the trans then the current picture shows. My concern is if you have a new shaft made, (they can't add to your existing shaft) it will bottom out at some point, and that would be as bad (or worst) then not being in far enough.

When your picture was taken, how are you lifting the car? If you are unloading the rear suspension, you are not getting a true picture of where your drive shaft is normally riding. If you are jacking up the body and the rear axle is hanging, that may be as far as the shaft comes out of the trans, and that would be OK (unless your offroading and lifting the rear tires off the ground a lot.)

Disconnect the drive shaft at the rear axle, and push the driveshaft into the trans until you can't see the "clean" part anymore, and measure how far that is from bottoming. Then get back to us. Gene