Some misinformation there. Nobody refers to Ruger single action production changes as "generations" so it would be best not to include this terminology to add to what is already a difficult lineage to understand.
The first Blackhawk was the .357 "flat-top" introduced in 1955. This sixgun sported a Colt SAA-sized frame. It was continued in this frame size when the top strap was changed to what we refer to as the "eared" models in 1962.
The second Blackhawk was the .44Mag "flat-top" introduced in 1956. This model sported the same Colt-sized grip but an enlarged receiver to handle the .44Mag cartridge. These guns were discontinued in 1962.
In 1959 the Super Blackhawk .44Mag was introduced featuring the same size receiver as the flat-top but with a longer, all steel grip frame with square-backed trigger guard and the "ears" around the rear sight.
Later, Blackhawks were introduced in .30M1 Carbine, .41Mag and .45Colt. All these guns were produced on the large, Super Blackhawk sized frame. Up to this point, only the .357 was built on a smaller frame.
The entire single action line received a major redesign with a transfer bar action and the New Model Blackhawk, Super Blackhawk and Single Six were introduced in 1973. Thus, Ruger begins referring to all pre-`73 single actions as "Old Models".
In New Model production, all Blackhawks (.30M1, .32H&R/.32-20, .357/9mm, .38-40/10mm, .41Mag, .44Mag/.44-40 and .45Colt/.45ACP) are built on the same large frame from 1973 to present. Exceptions noted below, read on.
The Vaquero was introduced in 1992 as a fixed sight version of the Blackhawk and again, on the large frame.
In 2005, Ruger phased out the large frame Vaquero in favor of a new mid-frame New Vaquero. They also introduced a new mid-frame .357 Blackhawk for its 50th anniversary.
Ruger has also made use of this new mid-frame Blackhawk platform for its new .44Spl's. Ruger has also introduced a New Vaquero in .44Spl but mismarked them with simply "Vaquero".
So, to date, ALL .45Colt Blackhawks, New and Old Model, can handle "Ruger only" loads. The New Vaquero .45 is the only Ruger .45 that can NOT handle these loads.