Yup, we have a pretty good number of those systems out, where they really seem to shine is when you want "highway" gears in the diffs with big tires and a non overdrive trans. For big trucks, the 40-50:1 that the Doubler will give you is sometimes not enough for big rocks so the Doubler/Lomax combo takes you to 60-75:1 which works really well.
We can build the Lomax case complete or sell you the kit to put in your 205. It's nice to do it at the same time as the Doubler since you have to replace the input gear and machine a 205 case in most situations anyway. The Lomax comes with the short 32 spl input and the right case already so it saves most guys about $250 to do the Lomax instead of the stock 205.