I went through the archives looking for a definitive answer to whether the sc400 especially 94 came with a lsd. Reading the archives, I think the opinion was leaning torwards no.

 

Go to Lexus.com, click on the Owners section, if you aren't already registered then register. Type in your correct VIN number and once inside, the page will tell you every single feature your car has, including LSD. There are also TONS of methods for finding out physically if you have an LSD or not. Search the forums for them.