Automatic Transmission problems of the 2006 Chevrolet Avalanche

Driving home last night, I lost 3rd and 4th gears in my transmission under normal acceleration. I have an '06 Chevrolet Avalanche z71 with less than 89,600 miles on it. I have never towed anything except for a uhaul trailer once for about 250 miles. I was on the highway when this happened, traveling 50-55 mph when it occurred. I was able to coast to a stop on the shoulder of the highway without further incident, however I was almost rearended by following traffic the moment it happened because of the sudden decrease of speed without warning. The transmission gave no warning before it broke. I still had 1st and 2nd gears as well as reverse. I have spoken with a mechanic and he estimates repair costs to be around $3000. I have checked several forums for people who have experienced similar problems and have found that this is a "common" problem happening to Avalanches that are 2-6 years old and having as few as 14,000 miles on them. My truck is out of warranty, but this is a pervasive problem that has existed since 2002 according to other Avalanche owners. The forums I found the information on are; chevyavalanchefanclub. Com, avowners. Com, and chevyavalanche. Com. This is more than an isolated incident, having happened to many people who own Avalanche's as evidenced on the forums. This defect is known by gm as evidenced by there own technical service bulletin number "08-07-30-027 June 08 â â â a/t - no movement in drive or 3rd gear". It is a flawed design or flawed parts are being used. Gm should recall all affected trucks with this particular transmission and take corrective action before someone is fatally injured due to a failure on a congested highway. An investigative look at gm's repair records to see how many trucks have been in for repairs, that have experienced the same or similar failures, would probably warrant a federal investigation into the safety of this product, and whether gm should be compelled to institute a recall.