Answer:
The starter is located just behind the V-8 engine and on the top side behind the
firewall. This is a time consuming job if you want to do it yourself -- that's what other 92' LS 400 owner told me,
He told me he had to take down the transmission in order to access the bolts of the starter !!!
In order to separate the transmission, you have to take off the drive shaft as well !!!
Also one reminder, CHANGE THE POSITIVE battery cable which links the starter AT THE SAME TIME because you don't want to change the cable for all this hassles .....
'good luck'