Several years ago Savage made some small changes to the MKII 22 Long Rifle receiver so that production could be streamlined and named it the "E" receiver. The major change in the newer "E" receiver is that it is slightly longer then the early models and the magazine well has been moved forward.
The easy way to tell what receiver you have is the receiver's length. The MKII 22 Long Rifle "E" receiver is 7 3/4" long and the MKII non-"E" receiver is 7 1/4" long.
The model 93's are chambered in 17HMR(93R) or 22WMR(93)(Magnum) have changed very little.
All MKII rifles are chambered in 22 Long Rifle and use a rectangle cut-out for the magazine opening in the bottom metal.
All model 93's are chambered in 17HMR(Hornady Magnum Rifle(93R) or 22WMR(magnum(93) and have a trapezoid magazine opening in the bottom metal.
The basic inletting of the stocks are the same between the newer MKII 22 long rifle and the 93 magnum rifles, the only real difference is the magazine bottom metal plate.
The synthetic(plastic) stocks are inletted for a bottom metal plate that is about 4-1/4" long while the wood stocks are about 3-3/4" long regardless of caliber.