Prices for used late model medium and heavy-duty trucks are down slightly, according to vehicle industry data provider Black Book.

It new report says 2011-2012 year medium-duty models show a decline of $633 this past month, which is $8 less than the decline of February’s $641 drop. The older 2003-2010 model year trucks didn’t fall as much, with a decline of $223, compared to the February’s decline of $354.

“This is a positive sign that the medium duty wholesale market may be ready to stabilize,” said Ricky Beggs, editorial director at Black Book.

On the heavier side of the industry, he says a drop of $500, or 0.7%, for the 2011-2012 heavy-duty construction/vocational trucks and tractors is the lowest depreciation for the late models segments. Heavy-duty over the road tractors are not far behind dropping $556, or 0.8%, while heavy duty regional tractors were the hardest hit segment depreciating $645, or 1.1%.

“There are a couple of models in each of these categories that have done very well lately and they are responsible for the overall low depreciation figures,” said Beggs. “We expect certain models to continue to maintain strong numbers at auction for a while, however all the heavy duty segments may not fare as well in the short term going forward.”

The older group of 2003-2010 heavy-duty units showed similar results. Heavy-duty construction/vocational trucks and tractors posted a $310, or 1.0% slide, while heavy-duty over the road tractors dropped an average of $247, or 0.8%. Heavy-duty regional tractors retained their values better than any of the other heavy-duty segments for this period only depreciating $206, or 0.9%.

Beggs said trailer values are relatively stable and many have increased in value over the past month. “Looking at all 12 trailer types we evaluate, we find that they have increased an average of $327, or 1.18%, from March to April,” he said.