the number of cylinders is not really the ?- you could look at displacement and/or power output.
if you want to hold 70 up the mountain grades- it may be tough in a 9000 pound van pushing through the air.
and cost a penalty in MPG and maybe engine and tranny heat
sometimes it's just better to get in the slow lane
for my van which is on a 2005 chev 3500 w 6.0 L ( 305 HP) and 3 spd w OD- we get about 16 MPG at 65 mph on the flats.
a domestic built ( to discern from the European designed current ford or dodge) ford, dodge, chev van shares major parts with a billion trucks and cars.
parts and service are available anywhere, from anyone, with parts from autozone or napa.
the only concern ever would be finding a lift with the height or lift capacity- many garages and car dealers do not
I veered towards the chev as I have other gms and am familiar with layout, have common tools, manuals and filters etc already.
for instance I know that a mobil1 oil change is going to cost me about $45 at home, serpentine belt is under $25 and the idler pulley is $12- this takes a 15mm socket to change ( I know this because I had to do this on my pickup).
I just did the shocks and my cost was $330 and it took me under 2 hours at home.
there will always be a design/part commonality within a brand, so that saves me trying to guess how a ford works (and vice versa for a ford owner)
i have rented the ford v8 & v10 E350 pass vans for work and do not like them- we found the mpg to be poor ( but that is me).
dodge got out of making tradesman type vans and started selling sprinters when owned by benz, and now sells fiats.
i rented a fiat based van in ireland and it was great- but again I don;t think it would fly up the mtns of CO