Quick transmission question

[iceman1110]

I have a 1992 SC400 and the transmission finally gave out. I've found a engine and transmission out of a 1990 LS400 at a local salvage yard with 110k miles on the pair and they would sell me the transmission off of it for $300. However when I went into pay for it they say it will not fit a 1992 SC400. They will not return it once I buy it so my question is will this transmission work before I go and waste my money? Hopefully it will because that is a hell of a deal to pass up. Also if it will not fit does anyone know of a reasonable place to pick up a transmission? Thanks in advance.
-mike