Getrag had shifted the remanufacture of its WM5G1 and WM6G1 gearboxes from its Getrag America facility to an outside firm, Component Remanufacturing Specialists, Inc. (CRS). Apparently, Getrag has been supplying CRS with the necessary parts to repair these units all along. Therefore, there exists a "well-oiled" mechanism for getting parts out of Germany. Mr. Donnelson states that CRS is willing to sell parts directly - either to dealerships or to individuals.

This is a win-win situation because CRS has a lot of experience with these parts which should result in rapid and accurate order fulfillment. I would suggest however, that each of us do our homework before calling CRS so we don't expend too much their time troubleshooting our gearbox problems over the phone. Remote diagnosis is something that they aren't set up for, and may cause them to have seconds thoughts about selling direct.
Component Remanufacturing Specialists, Inc. (CRS) 
400 Corporate Drive 
Mahwah, New Jersey 07430 
Attention: John Davis - Parts Manager
 (201) 512-1700 ext. 331
1st/2nd each have 3 rings. The blocking ring is the one that mainly wears out, but there may be damage on the others. Or you may want to replace them all as they don't cost too much. 1st and 2nd gear each has its own separate set of rings. The remaining speeds (3rd-5th and reverse) just have one synchro ring each.
C46 1st/2nd Outer ring 31.13
C47 1st/2nd Blocking ring 15.03
C48 1st/2nd Inner ring 23.93
C45 1st/2nd Set of three rings 70.09 Times 2
C11 3rd/4th Synchro ring 22.95
C63 5th Synchro ring 65.40
C74 Reverse synchro ring 68.00
296.53
There are no actual case gaskets. Case joints are filled with sealant, Mitsubishi P/N MD997740.
B06 Output shaft seal 10.25
B07 Driveshaft seal, driver's side 4.60
B31 Driveshaft seal, passenger side 4.40
B32 Oil fill plug 1.18
B33 Oil fill plug gasket 0.05
B52 Oil drain plug 3.08
B53 Oil drain plug gasket 0.05
B59 Rear plug(Input shaft plug) 1.18
24.79
The rubber plug in the back is part B59, and it costs $1.18. I don't know what purpose it serves; it's not a drain, filler, or breather. I may be able to figure it out when I pull mine apart. There is a gasket ring shown on the drawing (B60), but CRS doesn't stock it. They say to coat it with Loctite before assembling. I'd replace it, rubber deteriorates.

Information in this thread compiled from this thread http://www.3si.org/vbb/showthread.php?s=&threadid=73467

THanks to everyone that made the availability of these parts a reality.