Lexus Repair: Lexus RX300 2000 - Auto Transmition Issue, lexus dealer, lexus rx300

Question
My RX has 86k on it.  I am the 2nd owner.  I bought it in 2003 at 42k.  In the last few weeks on three separate occasions I have had a problem when the car is started (cold or not) and it is in park, I press on the break and push the button on the stick to release from Park to Reverse.  The gear shifts into Reverse and the car rolls, like it is going to go into Reverse and then stops, and it won't go into Reverse, even with some pressure on the gas.  It takes about five minutes, going back and forth between Park and Reverse before it finally goes into Reverse.  I have not had this issue in any other gear.  I have just taken it to the Lexus dealer to have them look at the problem.  After having the car for 3 days and not being able to replicate the issue, they were able to discern this morning that it is a problem with the transmition and it will need to be replaced.  They are telling me that it is out of warranty at 70k but are willing to help with ½ the parts cost, bring my totally cost to just under $3k.  My question, is does this sound like a whole transmition issue, I am I really in for a new transmition?  Also, how long can I go (approximately) before it goes out?  I just can't fathom dropping $3k on a car that is only 5 years old.  Please advise.

Thank you!

Answer
Hello, It sounds about right. If you have maintained the vehicle per Lexus suggestions (changing the trans fluid every 15k miles with genuine Lexus fluid) I would try to get them to cover it all. But 1/2 is better than nothing so you want to be careful not to loose that.