You're fine. The heater really just takes the place of the heater core and blower box under hood, requires 2 crescent shaped brackets to do so. It should have more air output that the heater core blower, at least it feels that way when I run my fuel fired heater on a test bench.
Not many people have or use this type of heater, I think maybe a few reasons. A lot of members live where they don't need a heater at all, members park their recreational truck during the winter, and/or these heaters are somewhat picky and not that reliable. I work with a few vets who say in tanks where these were common, they never worked.
I've had decent luck by priming the wick first. Pull the igniter out, pour diesel down the tube, let it soak, then reinstall and try it. Will smoke like crazy due to excessive fuel, but run good during and after that.
The one you are speaking of should be a 30k BTU unit. There is also a 60k BTU one which is much larger, I have that for my cargo bed, again, not installed. Test fire your heater first before you do the work of the install. It is somewhat simple, supply pressurized fuel to it, the hi/lo is just a timed circuit which gives the fuel supply solenoid 2 different pulse rates. You should be able to run the heater on low at any temperature. It should not run on high if testing indoor, as the internal high temp limit switch will shut it down.
