Hello again,

have done some more investigations on my inspiration-image HD followed by some websearch.

That bulldozer was built with Bryce and DTE/terrains even before 1999!

I just found the according R'osity Forum thread. (Whereas the contained url of this tutorial site has expired)
http://www.renderosity.com/mod/forumpro/showthread.php?thread_id=116325

The artist's name was "dtx", "dtx_" and currently seems to be "dtxart". I found several hints that these old DTE tutorials were done by a certain Peter Small.
His current site is here, though without that old bryced stuff: http://www.deeptextures.co.uk/portfolio.htm

Great News: Some old "Deeptextures" tutorials and even that of this "Oracian Tractor" are still online here:
http://homepage.ntlworld.com/dtxart/Chaffrme.htm

:)
Hubert

"All that we see or fear, is but a Sphere inside a Sphere."     (E. A. Pryce -- Tuesday afternoon, 1845)