There were no unit conversions given on my DAT exam. I did have a couple questions in which you had to use dimensional analysis and convert between units but they were pretty fundamental. I would know the basics such as how many feet in a mile, how many ounces in a pound or a gallon, etc. For my test they also had word problems with made up stuff that kind of gave you the unit conversions while reading the problem and you had to convert between them. Also, the units were made up units in some of the problems as well.
I agree with the above reply...know the basics because that's what they expect you to know for that section. You shouldn't memorize how many cm in an inch or something like that...