Gday mate
My photobucket account is down at the mo', but I may have what you are looking for if someone doesn't beat me to the punch...
I'll keep you posted
Brad

Hey again
I didn't have nearly the shots I thought I did, but a couple of close ups which may serve you well...









As you can see there is some variation. Most have dried mud caked solid under each track skid, which clearly traps plenty, and doesn't get removed easily.
The fronts of each bogey housing get a good covering of mud, as does the outside of the housings. Amongst all this you can see that the rim of each bogey wheel gets a good metallic shine to it through rubbing on the inside of the guide teeth. You can show spattered mud on the hull tub. Hard to find photos of mud spattered fronts and rears, but as you say you have a fair idea, and if you picture what would impact with the ground during movement you would know where to add more, such as the towing clevices front and rear, towing pintle can be encrusted etc etc. The outsides of the tracks would throw mud spatters along the lower edge of the hull sides.

Here is an example of how I portrayed mud on the rear of an M4


Hope this helps
Brad

No worries mate.
The effect you have achieved is looking good! To really set it off I would focus more on having the whole bogey assembly dust-covered (Check out the photo again; look at the difference between the running gear and the hullside) than adding too much in the way of grass. What I have found is that to replicate grass in the mud realistically is to actually add static grass into the original mix before application. Looking closer at the photo you can even see where the dirt/dust has been worn off the tyres by the track pads, leaving small repeated lines of mud where it penetrates the gaps...
Good start!
Brad

Hey adR
I like what you have done, not for the least because of the first use of the word detritus in a long time!
The logic seems sound reagrding mud on the exhausts, but the main question here is just how quick the deterioration was of the exhausts? Too often this is soooo overdone, especially on German tanks, as I figure that the attrition rate would mean that they wouldn't have the chance to get so rusted? Who knows for sure... SO basically, what is the time frame for your Mk. III?
To me the specks you have applied still look a little too uniform, and could benefit from some haphazard exra big clumps.
Keep the updates coming!
Cheers
Brad