For the antenna, i used a bristle from a broom. I was looking for one from a local hobby shop when the owner was brushing off dust. It's about the perfect diameter for my 1/35th M1a1, i just had to cut it to length. AND!!!!! it's bendable, so you can tie it down.
As for the dry brush, i used i beleive it's Raw Sienna (i'm at school, can't look at it now) and it looks like mud and dirt on the wheels.
I also did a flicking technique, it's where you put alittle paint on the end of a brush, and flick the part you hold.....this will give you what appears to be splatter marks
hope i helped