I just stole this picture out of the WTS Forum, but it shows the correct characteristics for an 8mm Mauser charger.
The 8mm chargers are the only ones out there that have the three humps on the siderails (and, yes, that third hump in the middle IS used to charger-load some 8mm rifles).
There are a couple of variants out there as to the construction of these chargers, though.
There is a 'one piece' charger that retains the cartridges by having 'bent-up-ends' on two tabs cut into the bottom of the charger, and the 'usual' charger is a two-piece design, with a separate retaining spring, much like the .30-08 charger you have.
A lot of people find the one-piece chargers to be a pain to use, but with a bit of TLC, they will work just fine. (After all, the Germans got through WWI using the one-piece charger, and until the US troops showed up on the ground in Summer, 1918, they were well on the way to winning that war.) There are also variations (usually by the country that manufactured the chargers after WWII) that will make the chargers either a bit 'tight' or 'loose' as to how they hold the cartridges and will make stripping rounds out of the 'tight' chargers somewhat more difficulr.
In any case, if you can get your hands on a few of these, you should be good to go.