In my opinion and according to my experience the bolt handle has not been altered.
Both 66' Mauser are of the first type but the stutzen is older and still has a forged bolt handle while the rifle version is equipped with the new welded handle for lower scope mounting (circa end of 1967 start of 1968)
This is difficult to see with the provided photos but the stutzen must also have a shorter rib and neither model has a separate bolt stop.
The Mauser 66 is one of those rifles that were born near perfect and have evolved in the wrong direction of simplification.

DORLEAC
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