I use MPHD on the frame of the truck. So wash the entire underneath of the truck down as best you can, then start spraying down all steel parts. I also found that you can use a foam brush to get to the hard to reach areas, or areas you are afraid you didn't get to the first time. Given that the body of the truck is aluminum, I lightly sprayed some areas of the bed, but didn't bother much with the body of the truck, I just made sure that all exposed steel areas are covered.
I then use Bioshield T9 on the shocks and front springs given that the MPHD is a yellow haze when it dries.
I also noticed some exposed steel on the front a-arms. So I bought some krylon paint from Home Depot, matte gray, and painted over those areas to keep that from being exposed.
Prior to the MPHD, I also washed and waxed the rear fenderwells, then installed the husky wheel liners.
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Overall, the MPHD will last about 1.5 seasons. So you'll do touchup work next fall (most likely with the brush to avoid having to cover and tape off the entire truck again), and touch up the frame or pans or other areas. T9 is an EVERY year application.
I did this for my Gen 1 truck and she looked really good for 8 years old. Did rust start to appear at welds? Yes, but had I kept the truck, that was a quick sand/paint/recoat. I didn't have a speck of rust on the physical truck body.
I did notice that this Gen 3 does not have those big frame holes underneath on the body under the doors like the Gen 1. For those I used PPF to cover those holes and keep the rust out. So that was one less thing I needed to do.