Dennis, I haven't seen a 3gal keg. Have any pics or links? The Cornelius kegs are pretty small and easy for homebrewers. A friend of mine is a serious homebrewer and I'm getting back into it, but plan to stick with malt extracts.
I know they are hard to find. You can check with my brew guru, Ray Ault at
http://www.winemakingbrewingco.com/
He does carry a wide range of products and may be able to help you find one. They are perfect for the fridge. I loved making beer but none of my buddies liked good beer and I made too much. My waist line said I had to give it up. But the genes go on, I gave all my equipment to my nephew for home use. At work, he is the Brewmeister for North Coast Brewing in Fort Bragg CALIFORNIA.
I used whole grains at the end but one of my best was a Russian Imperial Raspberry Stout that could lay you low but you did not care. It was done with extracts, they get better all the time.
Good luck with you keg setup but remember to disconnect it and don't park in any "homeless" areas. :drunken:
Slainte.