First, DDiggler, welcome to Predator Masters! Are you new to predator calling or just this board? Lots of fellers check in here who have built their own callers using quite a varied assortment of stuff. Homebuilt threads tend to get overwhelmed sometimes by the numbers of commercial caller posts, but there are a whole passel of them in the archives. You've probably seen the main Predator Masters page; less obvious perhaps are the links to the Tech Pages where some of your hook-up questions might already have been addressed.
I'm guessing that your Nady receiver is one of the flat chassis-mounted units and not a camcorder-mounted one, as are the 151VR-LT and 351VR-LT. Even so, it might work okay if it has a good frequency response, though it might also make for a relatively bulky finished caller.
The wall wart, if you still have it, should be badged with the voltage and polarity of the plug on the case (I'd expect its output to be 12VDC, but I could be wrong). If it's not marked but the wall wart still works, won't take but a moment with most any old VOM meter to figure it out. You'll want to pay attention to preserving correct polarity, particularly.
Depending on how old, i.e. if the unit is older than the ones that have a full frequency response, you might be better served buying a newer model (DKW-1 LT models can often be found for
