Automatic Transmission problems of the 1996 Toyota Avalon

I bought a used 1996 Toyota Avalon. It was covered under 6 year / 100,000 mile warranty. The warranty expired in March of 2002. I now have just over 100,000 miles on it. When putting the auto transmission in reverse from park or neutral the transmission engages violently. Although it does not "bark" the tires, it is quite severe. My local dealership said that the transmission valve body gasket(s) were the likely cause and they had my car from 9-3-03 to 9-5-03 replacing them. They said that a TSB had been issued detailing the replacement of these gaskets, but no recall has yet been issued. Toyota engineers changed the design of the lower valve body gasket in 1997 (tc00197 Apr 1997) because of this. There is a possibility that the direct clutch portion of the transmission could be damaged due to the cross leak from the gasket. My question is- why did Toyota not recall these cars because of this? two valve body gaskets are less than $30. 00 (Toyota prices). I am not sure if the new gaskets will interchange due to construction of the valve body, bore, etc. All I know is that the local Toyota dealer replaced these gaskets and I have the same problem that I did originally. The local dealer was great to work with (they charged me no labor because they did not fix the original problem). I am now stuck with a car that I have put roughly 60,000 miles on since paying over $20,000. 00 for it (before trade-in) in 1999. I can't trade or sell this car untill I get the transmission fixed ( install a new or rebuilt unit). The cost of a rebuilt transmission and installation would likely be over 30% of the cars current value.

After vehicle was placed in park and the ignition turned off, vehicle rolled down a slight incline and impacted a brick wall.