Is this a Dana 25 powerlock?

Doesn't Howard have one? or at least a pic of one?

 

The U.S. military was the one to initiate limited slip differential development.
The original Thornton Powr Lok was developed specifically for the Dana Model 44 rear axle.
The 10 spline units would be during what I consider to be the developmental period. (circa 1954-1956)
I would expect the early production 10 spline units to be of a previous cone clutch design.
Parts for those early Powr Lok units are apparently non existant.

The Dana 44 Powr Lok was perfected and standardized before the late 1950's.
Dana 44 Powr Lok development directly led to the developement of the 19 spline rear axle shaft.
The change over to 19 spline axle shafts became the new standard by late 1956.

The Dana 25 Powr Lok was not developed nor was it ever available before the early 1960's.
The D25, plus the later D27 and D30 Powr Lok units were all designed virtually identical to the standard D44 design.
That in part explains why some internal components are interchangable between the units of various model axles.

In the early 1960's the Dana 44 Powr Lok with 30 spline side gears also became available.
The early Dana 44 @ 30 spline design was changed and standardized a few years later.
That simple change only effected the 30 spline side gear and clutch ring configuration.
The early 30 spline side gear components are interchangeable with later 30 spline side gear components.