so I did the leaf springs today

I did the leafs they were a breeze with the impact gun. Problem was when I replaced the shocks the heads of the volts cracked on both side (yes that part I did by hand). We had to drill out the bolts retap and go from there.
I noticed that the under body is not painted and rust is starting to form. I want ti power wash and buy undercoat spray. Anyone ever did it?

You want to scrape off as much rust as possible and then spray rust arrester. Let that cure and then paint with a rattle can. Let that cure.
Undercoating spray should be used only after the rust arrester and paint.
Undercoat spray alone only insulates the rust which continues even faster.

I agree with obxxj that is how I did it came out awsome. Got every thing at advance for around 30$