Hi model builders,
@Uncle-Heavy, hi Robin, the funny thing with Kitmaker website ads, I generally get two types, including websites for heavy equipment auctions, and generally inexpensive model kits! via websites or ebay - These are not usually the newest and best kits, and certainly not the fancy pants MFH kits, just regular kits, that I don’t feel to guilty about buying - lol -
@justsendit, hi Mike, well, it seems we have been posting here for so long…
long enough for me to see you’ve been in an aircraft phase lately which I don’t recall you doing, say, ten years ago!
And for now, I’ll just keep truckin! and cutting up truckloads of styrene!
@Dioramartin, hi Tim, haha - first, thanks - and second, you know what - I screwed this final post up. I got lazy and only did step one with the photos: outdoor pics. This is fine, but it seems to me, after putting the time into the builds, I should have better photos. Alas, the server won’t let me upload any images, lol, so, you’ll have to take my word for it!

Aha! It works with Flickr! so, I’ll keep going!





Ok - that feels a lot better! And, I think the trucks show their true majesty!
OK, back to serious business, and the paint. The base on both trucks is Tamiya from a can. As for the area you asked about, and well, the rest of the truck, it’s a simple 90 step process…no, maybe 83 steps!
…by this I mean, each truck has many layers of repeated washes (all Vallejo Model Air) of varying degree of dilution, and a final highly diluted wash of dust (LifeColor).
But, before the wash in the area you asked about (starting with the axles and hubs), a few layers of more or less solid coats of paint went down, also in layers. First was Anthracite grey, which I use as a starting color for all areas with rust and/or scrapes. I figured out along the way that this color fully covers the base color - so that when you get to rust or whatever type of decrepitude you are looking for, doesn’t appear to be ‘floating’ over the base color, and instead appears to go to the base metal.
I make up my own rust color with anthracite, burnt umber, white, and orange - only varying the amount of each depending on the look I’m after. This is dabbed onto the anthracite base, intentionally staying in that area only - but not a solid paint application. While it’s still drying, I dab the brush with the rust still on it, into some water and dilute it to my liking and go over the area and surroundings again. It’s ok if some of the rust washes off, and if the wash creeps out and about.
For the leaf springs, I did the same, but then followed up with a thick almost non-wash of Ivory (sand beige) to look like mud and dirt (the point is, dirty, rusty leaf springs, not beige leaf springs - and, while at it, splash some of the wash from this around too.
Once all of the vehicle has whatever amounts of the aforementioned decrepitude, a wash of diluted LifeColor dust is applied everywhere. Once you’ve done this a few times, you can get the hang of how to use it to help fade paint, great pooling, and so on. I use a stiff, beaten up, and frayed old brush for this. In addition to dulling all of the colors, it also helps to blend edges, so that the final result doesn’t look like a blue truck with various splotches painted onto it. Simple as that 
@Stryker45, thank you very much! It’s funny, each of the trucks probably have the same amount of detail work! But the changes on the blue version are huge - lol - and awkward to assemble, while on yellow, tiny, and, awkward to assemble! 
Thanks for having a look
Cheers
Nick 