There are many offerings for these on ebay and the like. Have you done an internet Google search for "2003 Ram Service Manual" ?
If your looking for a 'freebie' one, they are tough to find. I have a very extensive service manual library that has taken me about 10 years to accumulate. I have the tendency to run a search and dig as far as 100 pages into the results. For some, I've run the search every month for 2-3 years before I struck Gold.
This is one area where persistence often pays off, but sometimes it takes years. If your stuck and can't wait, then paying for one is best bet. :smileup: