I've noticed used car dealers have a lot of stock. New dealers both used and new are on the low end. That could be because new dealers only want the cream of used trade INS to sell.
Diesel gas on 25-55 series trucks. Seems to depend upon brand.
Ram trucks are pretty high percentage of diesel. I have seen a reasonable number of 25/35 series rigs with hemi's.
Ford and GM.
Ford is top in the DW C&C rigs, cab and chassis. Depending upon owners, varies on fuel version. Large construction, Kewitt and Atkinson doing the new light rail. Appeared that ALL of the Ford rigs were gas, be the C&C, or SW crew cab pickups. State of WA DOT trucks I saw over last two days, also gas for same versions. Saw one 650 that was gas too.
Smaller construction companies with C&C rigs varied around 50-50. Both for pickups and C&C rigs.
Wrecker/tow rigs, 70-80% Ram Cummins. Rest Ford psd.
Saw a few GM 45/55 trucks. Don't have the visual what to look for to see if G or D fuel. Less than 10% of that size rigs that I saw.
That's my travels around Puget sound from Seattle south to Olympia, west and north to Bremerton to Tacoma.
Marty