Leon's schematic is for the Sure Lube system on the Reliable, Inc axle. The old grease comes out the back side of the hub.
An equivalent picture for Dexter's EZ-lube (most TM's have EZ-Lube, I think) is at
http://dexteraxle.com/e_z_lube_system
The old grease comes out the front, right next to the Zerk where you are pumping in the new grease. Click "Product Flyer" for a bigger picture.
Both are pretty good, and easy to use, though a couple members have reported grease getting to the brakes. Don't know how or why.
Bill