For those who want to find locations where they served in Vietnam, I suggest starting with the "Where We Were in Vietnam" book by Michael  P. Kelley. It was published in 2002, and is still available for $39.95 or less. It may also be available in libraries or Vet Centers. This book has thousands of grid coordinates (561 pages of them!) for almost every sort of fire support base, patrol base, airfield and landmark that was of any interest to the U.S. military. It also has information on ordering maps, an index of 1:50,000 tactical maps, and a glossary of acronyms and military terms.

 This website has information on how to order 1:50,000 tactical maps of Vietnam from the war era: http://www.rjsmith.com/topo_map_info.html.

 The following part of the same website has  links to scanned 1:50,000 military tactical maps of many "popular" areas in Vietnam:
http://www.rjsmith.com/topo_map.html#bigmaps. 

 The 1:50,000 tactical maps are available from the United States Geological Survey (USGS), but you need to know specifically what you want. The maps cost $9 each plus an order handling fee. You can also get these maps from other sources, but they will be more expensive.

Another source is Omni Resources: http://www.omnimap.com/catalog/int/vietnam.htm. I believe the "road map" I ordered from them is item 65-52916 in the second group down the page (Northern and Southern Vietnam Travel Maps). It had way more detail and many more roads than the "official" Vietnam road maps you can purchase in Vietnam.

You will need to find the MGRS (Military Grid Reference System) coordinates of the locations you want to locate. Many of these are in Kelley's book. If you get the maps, you may find a few areas of interest, although only the larger base camps are typically shown on them. I believe you could probably find the locations with coordinates in a GPS without the maps, but having the tactical maps marked ahead of time with locations of interest makes it much easier.

The MGRS coordinates from the book look like this: XT 407-440 (the coordinates for Fire Support Base Schofield, located southwest of Dau Tieng). This is essentially the coordinate format for a single map sheet. The complete MGRS coordinate information can be found on the margin of each 1:50,000 map. In the case of FSB Schofield, it is 48P XT 407-440. On some maps of the 25th Division's area of operations, there are both "XT" and "XS" sections. Some version of this is what you need to plug into your GPS software (you may need to remove spaces and dashes -- check what your GPS shows as the format and follow it).

 IMPORTANT NOTE: Make sure your GPS can handle the MGRS coordinates and the Indian-Thailand grid. This is what is used on the 1:50,000 tactical maps. If your GPS and its accompanying computer software won't handle these settings, you might as well leave it home. The instruction manual for your GPS should have a listing of all the coordinate types and grids it will handle.

Before I left on the trip, I spent hours (probably DAYS...) finding the coordinates, marking the locations in red on black & white paper copies of the tactical maps. Our local FedEx/Kinkos made the copies for about $3 to $4 each. The B&W copies were much easier to use because my red dots for the locations of interest really stood out. The original maps have a color overprint for various things such as jungle, rice fields, rubber plantations, etc., so they are quite busy to start with.

I entered all the MGRS coordinates into the Garmin MapSource software on my computer. (This is not a plug for any particular product, but it is what worked for me on our May 2009 trip.) I bought Garmins World Map software to have better (but not especially good) road coverage in Vietnam. And keep in mind that many of the cow paths we knew way back when might now be a two-lane, paved road, so they don't show up on either the map or the GPS software.

I also imported the coordinates to Google Earth to get an aerial photo look at the terrain and surroundings, and then printed color images of various areas of interest. Basically you start with the GPS in MGRS and Indian-Thailand grid to enter the coordinates, and then you switch the GPS to Latitude/Longitude and WGS-84 grid. Unfortunately I can't do a tutorial on how to do this for all the different types of GPS receivers on the market, but if you play around with it you should be able to figure out how to do it. I believe having the aerial images from Google Earth is extremely important -- we found a bridge on one aerial that didn't show on any map or the GPS. Taking the bridge saved us probably an hour of detouring.

I brought an inverter to Vietnam to give me 110-volt power for my netbook (small laptop) computer in the van. I plugged the GPS into the netbook, and it fed the signal to Garmin's nRoute software. This gave me a moving map image on the computer screen as well as the GPS. I had the GPS set to show the location in MGRS coordinates on the map screen, which we could use to make a quick comparison to the 1:50,000 tactical map to see where we were.

Whenever we got close to the location of a fire support base, I counted down the MGRS coordinates aloud while Thi, our guide, watched the map and used his thumb to keep track of our position just like I did when I was the platoon leader's RTO in Vietnam in the 1960s. I only had to explain the MGRS system once to Thi, and he was off and running.

One caution: Because so much has changed in Vietnam in the 40 years since we were there, it was often quite difficult to determine where a base was located 40 years ago. We drove back and forth through the location of FSB Schofield several times before we realized where it was. Even though we were moving slowly in the van, it was too easy to look away from the GPS and try to find something that looked familiar. It is an eerie feeling to look around and sort of recognize the area, but not be able to find any sign of a base. The only bases that were easy to find were the ones now being actively used by the People's Army. The other factor that adds to the difficulty is that the two-letter, six-digit MGRS coordinates are only accurate to 100 yards on the ground.