I know for sure the 94-95 LS models were 24valve sohc 3.0's, But I'm guessing no one has ever put a manual trans onto one.

I just got a 95 SR and man do I miss the 5speed from my mighty max. I'm pretty sure the bellhousing pattern is the same between all the 6g motors, So I can't imagine why this could not be done with the right flywheel and clutch.