Don't waste your money....
Before you all commit to spending thousands of hard earned cash, have you looked and searched for everything on the shuttle valves?
There has been numerous threads over the last couple of months and the trend was that the shuttle valve's are only needed to be replaced.
Look here
http://www.hummerknowledgebase.com/brakes/absmod.pdf
And here
http://www.aulro.com/afvb/technical-...-3-amigos.html
There are only three parts which make up the modulator.
1. Shuttle valves - $120
2. Connector Plate - $1200
3. Valve Plate - HEAPS.......
Your modulator collects dust more than anything else. Why would it wear out so much that it requires a TOTAL rebuild and at great expense?
The shuttle valves fail due to lack of use. Everything else should last a lifetime.
I replaced my shuttle valves and the problem was solved. The next problem area is the Connector plate and there is no evidence of any problems with the valve plates.
Spend your $120 on shuttle valves and then take it from there.
I think a total rebuild is just not needed.
EDIT: My D2......January, 1999 build.