Measure the base (width of the fuse where the gear connects), the height (from fuse vertically down to axle, aka landing lenght) and the width between the axles.

I used the Dubro Super Strength Landing Gear. It broke because I drilled too many holes in it, but the composite/fiberglass landing gear is great because it doesn't bend. The gear I used looks great, gives you the height you want, and the width between the wheels.

I have the Dural landing gear coming (should be here by now?) and can tell you how that works on the Dolphin. Again, it's aluminum so it will bend eventually, but not as easy as the stock Dolphin gear.

I think this would be the best, but of course it's the most expensive:
http://www3.towerhobbies.com/cgi-bin...?&I=LXHBP8&P=0