Question about '74 radio hole...

Are '74 SP radios different from say a '72 standard beetle?

The hole in the dash of the '74 is much larger than the hole in the '72. I put an indash late model MP3 / CD player in the hole for the '74 and it was too small. The hole in the '74 looks factory, (even cuts, square holes with rounded corners, cut out for clips on radio to snap in, etc..) it even has non marred padding at the edges. It looks like the radio was just physically larger than the one in the '72. The new indash player is 1/4" inch on the top and sides too small if it is sitting centered on the bottom of the hole in the clip part for the back. I have "made it work" by clipping on some small L bracket to the top of the aftermarket unit to fill the gap up top, but the sides are still short.

Any way, just was curious as to what the deal was...
KC