Is my drive shaft too short?

Don't skip over good advice. Read post#5. Only 4 fasteners hold the drive shaft in. That's less than five minutes worth of work to determine how much the slip yoke engages the splines on the output shaft. THAT'S what's important. Not how much of the slip yoke is sticking out.

That said, the locating pin on the new springs does look to be in a different location. Put a tape measure on it.