I feel the need to clear some things up, regarding the Unimog axles.

First point is that the Unimog can be the size of a CJ5 or bigger then a HEMIT (SP?) They share the portal axle, coil springs, and the torque tube as defining features (except the new Freightliner).

416 and 406 (for all practical purposes) are the same. The 406 has a shorter wheelbase, while the 416 (in my Avatar)is a bit longer. MB is still making NEW parts, and provide 100% support for these vehicles IF (and only IF) you know who to call.

The 416/406 has an air accuated locker, and can have 4-drum, or 4-disc brakes. Both drum and disc brakes work equaly well, with drum brakes reccomended in muddy/wet applications. ALso, the 416/406 has a few R&P options that will give you standard, Fast, and Super Fast ratios.

The 404, on the other hand, is much older. I'm not as informed on these guys... There's still a lot of NOS parts, if you know where to look. Drum brakes can be modified to run the 17" rim. Lockers are mechanical, as I understand it, and have no R&P options.

I'm trying to find more information on Toy calipers on the 416/406. I've never hear of it, but I don't hang around the champion crawler crowd much.

I'd be happy to answer any 406/416 questions, as I have a 416 in the driveway.