Single linear ball bearings?

My post yesterday on dual linear ball bearings prompted Matt to look at some of the schematics for the other manufacturers. He didn't seem to believe that some of our manufacturers would be so cheap as to only use one linear ball bearing like Makita was implying. We did a little research, and the results were astonishing.

DeWALT DW708

This particular model of DeWALT has single bearing on the lower of the sliding rails. It's not possible to tell if it is a sleeve or a ball bearing, just that it is a bearing. However, it can't be purchased independently. It's part of an assembly (reference #121, although the 12 got clipped) for $370. Ouch.

DeWALT DW718

Admittedly, the DW708 isn't their newest model. The DW718 is probably a fairer test of their current manufacturing practices. What do we see here, then? One bearing, can't tell if it is sleeve or ball bearing, and it is still part of an expensive full assembly.

Hitachi C10FSH

To stop picking on DeWALT, I'm going to show a Hitachi now. Part #106 in the diagram is a bearing. They call it a "Ball Bushing". Just one, but we know for sure this is a ball bearing type.

Milwaukee 6497

Milwaukee has 2 ball bearings. WOOHOO! Wait just one second, though. That's part #6, and they don't go on both rails. They go on one rail. That's not exactly how it should be done. One rail is just sliding through a hole, the other has 2 ball bearings. Interesting.

I'll have to add in the Makita version as soon as I locate a schematic for it. This should be interesting.

EDIT: I finally got a solid answer from Makita on where the second ball is located. I have this entered in another post titled Makita's Mysterious Dual Linear Ball Bearings. It was a bit much to add to this already lengthy article.