I mainly use one of Harbor Freight's inexpensive meters (great buy when they hit $2.99):
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=90899

It has a 10 amp (DC) current range and works fine for this sort of stuff. A 1-2 amp drain will kill a good battery in a day. I recently found a ~200mA drain in my '85, the on-board welder control box had been switched on accidentally and the indicator light on it was on, killing the battery in a few days.