That explains it...
Just be sure and get the planetary with the splines that match the year of your shaft.
Spline pressure angles were:

'62 to '75: 45º
'76 to '93: 37.5º
'94 and later: 30º

The pressure angle is half the included angle (90°, 75°, 60°).

1993 Daytona, 5.50 at 130mph (1/8) 1.19 sixty ft (PG). Link to 572 B1 - Part 1