Someone on the SL list had the splines fail in the trans output flange, that would cause what you describe.

Put the trans in park and see if you can turn the drive shaft. ( it should remain locked )

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If I rotate ( the wheels ) them the drive shaft on the exit of the transmission rotates too.

If the shift lever is moved out of park nothing changes, no rotation on the drive shaft.
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Your two statements conflict each other.

Some transmissions wear splines in drive shells , clutch discs but I would not expect the trans to drive the speedo.