J.S. Machine, If you do not have a copy of "Machinery's Handbook", I strongly suggest you get one.
All the information you need and more than you will ever need is in there. In mine, (26th edition). it starts on page 2342.
There are different fits for different applications. Usually its a very tight fit on the width and slight clearance on the height. Page 2353 in my handbook has all the information you are looking for.