Toy train operating and collecting

Hello, I am new to this forum. I am actually doing this for my father who is an avid Lionel fan. His collection consists of O27 gauge Lionel. I am unsure of the pieces, but, he is looking for a transformer to replace the one which was taken from him after his house caught fire. He has described it as being able to power four trains, or at least having four sets of terminals. It was made around 1950(s) and rather large... roughly 8-10" wide by 6-8" deep and 4-6" tall. there was a lever on either side to control the speed and seperate levers for coal car, whistle... I don't know anything about this, but, I do know about the internet and my father doesn't. I love him very much and want to help him in his quest for the lost transformer. It is the final step before setting his track up. Any help would be appreciated.. I will check back on the forum or PM's. If I sound like a goober, I apologize, I don't know much about trains.

Thanks,

Lionelfan027

P.S. any pictures that I could print off would help for ID purposes...

Well you are in the wrong forum to get a lot of answers.  You will want to repost in the Classic Trains forum where the Lionel people interact for the most part.  The key element to your question is the number of trains the transformer controlled.  The Lionel KW transformer controlled two with top mounted levers and the ZW controlled four with side mounted levers and had a bullet nose design on each side.  Look for those two on E bay and you should find pictures and prices easily.