best engine/transmission choice for a dump truck - 26-33k GVWR

hello all,

i understand this kind of question is likely going to get into personal preferences and is largely opinion based but i'm still curious to hear about experiences folks have had.

i'm looking to get into a slightly more capable truck than what i have now. would prefer to stay with the single axle (space and access are important for me) but i would like to find something with more GVWR (~33k GVWR would be good for my needs).

my first truck was purchased from an aquantaince and it worked out well enough but i want something with a manual transmission (current rig is an allison auto).

what engine/transmission combo i should be looking for? i usually only haul gravel and i'm going to be buying an older truck (my budget is $12-18K). thanks all

a.