I've just purchased a 39 with a 4 speed that really growls. After having 5 advanced designs I'm not sure what is normal. Lucas and STP don't seem to help. The truck has a '59 235 which came with the original 4 speed trans set up for an open drive line. If I use that trans what is a good rear end that I can swap and still use my 16" wheels? Limited slip would also be nice.