I've got a pro sandblasting setup now after trying way too many times to strip the paint off of old trucks using other methods. There is just no other way feasible to get the job done well, and done relatively quickly than sandblasting. Used to take me like 3 weeks to get one of these trucks ready for paint. Now I can completely sandblast and paint one in just 2 days. My sandblaster and air compressor are probably the best most valuable tools I have ever bought!
Here's a couple pics of one of my trucks in my shop with my Schmidt 300 pound sandblaster. Fed by my Sullivan 210 CFM rotary air compressor. And yes, very important to have an air fed helmet fed with clean air. Unless you have a really good filter and carbon monoxide detector on your breathing air, it's not usually a good idea to use the air coming from the trailer mounted compressor either because when they get hot, the oil that lubricates the rotary vanes of the compressor, can actually burn, and create carbon monoxide that you are now breathing. People have died that way. I use a separate air compressor for my breathing air, and it is so nice to be able to be right in the middle of an absolute dust storm, and breathing perfectly clean air.
But yeah, like others have said, it takes most of a day with a good size blast nozzle, and air compressor, and it's taken me around 40-50 bags of sand per truck. I buy all my sand at Home Depot for $3.67 a bag I think. And it is well worth it to me! You can reuse the sand as well, but it tends to get pulverized and turn into powder that doesn't do much good other than obscure your vision, and it can be a real pain in the butt to sift through. So I've determined that it is worth it to me to just buy enough sand to last for the whole job, so all I have to do is open a new bag and pour it in the blaster without having to sift it.
But yeah, sandblasting is by far the way to go from preparing these old trucks for new paint! The absolute biggest problem with it though, is trying to get all of the sand out of the truck! You think you got it all out, and then you go to spray paint, and the air from the spray gun blows some more sand out of somewhere and it gets all stuck in your new paint! AHHHHHHHH!!! The first truck I sandblasted and painted, 6 months later, when I sold it, there was STILL sand coming out all over the floor board every time I'd drive it. I have no idea where it could have still been coming from!!! So count on that! There will be sand EVERYWHERE!!!!! Or whatever media you use. It will be in places you did not know it was possible for it to get in.
Another warning..............Remove ALL GLASS from the truck if you are going to sandblast! There is NO real good way of protecting it from being damaged other than to completely remove it from the area! I have damaged quite a few windows with my sandblaster! Cost myself a lot more money than it should have. I knew the sand would damage the glass, so I spent a few hours masking the heck out of all the windows and dash guages so the sand wouldn't get to them... It did not work. Sand found it's way around the masking, and it other places just blasted right through. So now, I just take the time to take all of the windows completely out of the truck. Saves me a LOT of trouble and money for new glass!
Oh, and another warning............If you are planning to sandblast, I have learned it is a VERY BAD IDEA to get grey primer. Ha ha. Newly sandblasted metal is almost exactly the same color as grey primer, so it is nearly impossible to see where you have and have not sprayed the primer!