Schuetzenkid,
The first Stevens 44 1/2 pictured is a Stevens model 47, with optional Pope lever, and heavy schuetzen buttplate. As with many Stevens rifles, it's tough to pin them down to one model, since Stevens offered many options within a particular model. The only way to really pin them down is to look at the front of the receiver. Mine is marked "047" there.
The second Stevens in .25-21 is closer to the model 51, except for the different lever of the Ideal Schuetzen, vs. the hooked lever with wood insert of the model 51.
Which lever does your 51 have?
Hope this helps.