Vinci might have that Crane spring compressor.... www dot vincihiperformance dot com. I highly recommend this tool if you can get your hands on it, it's the best and I've just about used them all. (this is when doing the springs with the heads on the engine)

I've used the More tool (that's the aluminum one that looks kinda like a rocker arm right?) it sucks unless you can hold perfectly still, as it slips sideways, especially when doing the rear springs against the firewall where you can't get directly on the tool and put your body weight over it.

I've used those, while building heads on the bench...won't do a whole lot of good with the heads on the engine in the truck though lol. If you don't have access to an air compressor, they sell the big c-clamp style that are manual and work sorta like big vise grips. I've used them also and they work well.