I used paint stripper for my ute and went through around 10 litres or so with around 4 of those just on the tray as the owner before me used house paint or some crap and because the tray was dinted it was up to 1-2cm thick in spots (ridiculous i know). I used a 100mm grinder with taught wire brushes heavy duty industrial stuff and worked great. I think i burnt around 10 brushes to do the car from top to bottom completely stripped it. I started off with a drill and got no where, absolutely useless.

As for Sandblasting although i have not used it on a car i have used it on restoring a couple boat trailers, ripped all of the dust and paint off but if not done correctly i have heard horror stories of it doing more bad than good. I have also heard you will never get that smooth metal finish back as it can do a good job of pitting it? Havent seen this but heard and read about it...
I haven't much to offer on the Soda Blasting, however i have heard good things about it, there is a good video on it at the Australia Soda blast website
http://sodablast.com.au/
Good luck with your venture!

paint stripper from Bunnings and wire brush (or 'coral') attachments to the drill

wore out 1 drill and about 6 attachments

i always though that sand or soda blasting was the way to go also.
but i have been talking to a few panel beaters, quite good ones i might add, and they have all said that paint stripping, although more mucking around and annoying, is probably the better way to go.

They also added that if the person doing the blasting is not very good he can do more damage than good...

This is just my 2c, but I've had trouble over the years with paint stripper never totally getting removed, and paint eventually peeling, or bubbling here and there.

It's not cheap, but I honestly reckon sandblasting (or blasting with some sort of abrasive media) is a far better bet. The paint seems to go on better and last longer.

I don't have any 20 year old paint jobs to compare it to, but I am talking about 5-10 years sort of thing.

thanks for all the info so far...

how much paint striper would i need for the whole ute?? any idea?

I used some industrial stuff from my local paint shot that supplies all of the local panel beaters, awesome stuff and from memory it was around the 25 dollars fro 4 litre mark.

yep, strippers like it rough. It helps with intercoat penetration and speeds things up.

I always rough out the paint surface first with gritty sand paper so the stripper has somthing to grip to and it work fairly well. I think i used K and H pink tin or maybe it was brown?

POR 15 very very very good stuff !!!

i bought paint stripper from supacheap worked fine.