Transmission Upgrade (Auto or manual)

[edinlexv8]

Hello Folks,
I have a SC400 and I have been offered a good deal on a used 5 Speed auto box from a 1998 LS400 (1UZFE engine same as a soarer). I am not sure whether to buy this or not. Are there any advantages in upgrading to a 5 speed auto?

I am not sure whether to buy this or not. Are there any advantages in upgrading to a 5 speed auto? I suppose fuel economy is one but not of a big concern as the gains are minimal. What about the top speed? What things I have to be concerned about when doing this upgrade?

I see a lot of the members upgrade from an Auto to a manual. What are the advantages of going manual? What are the options for manual W58, R154, V160? The first 2 being 5 speed the last one being 6 speed which is the best to replace the autobox considering supercharging is on the pipelines

Thanks