hey man...i broke my antenna the same way the very first week i had my car...i didnt have time to wash it myself so i went thru a car wash....u can pick up the antenna for an LS400 90-92 for i believe $70-$80 at a lexus dealership. in march of 93 they made a newer model antenna for some reason i don't no. to remove the old one, turn the radio on, and that silver ring unscrews that the antenna goes inside. once u remove that....remve all of the white cord from the broken one. place the white cord from the new one inside...there r teeth that will meet with thie cord and retract it. basically jus put it back together the way u took it out. good luck.
basic things u should get done to the car r probably new tires...an allignment. oil change. jus because it has low miles doesnt mean everything is great. the car could have sat a long time considering if they drove it the whole time they put somewhere between 2,500 to 2,800 miles on it per year. check the power steering fluid...make sure it has been replaced before if that sat the entire life of the car u should probably get it flushed out for probably around $50. there may be a few leaks but they can be fixed easily. dont get discouraged after u get the car inspected. and u should probably get a 2nd and maybe even a 3rd opinion on the car. dont go with what the first guy says. take it to the mechanic with a mind set of telling him u r about to buy this car and u want to know what he thinks. if they know u own the car they may sell u on things that could use fixing but not needed.
power steering flushes are completely safe if done propely. i recommend taking it to a shop and not buying the stuff u pur into it. most people think that power flushes cause leaks thru out the power steering system, but i have flushed out many cars and not ever a problem.
didnt realize u said 66k miles...thought u said 36k...that changes average miles per year to 4,500 - 4,800.