so firstly I'm sorry if I break any rules, this is my first ever forum post here so I'm not 100% on how everything goes. so for my suggestion, I suggest the beloved Mack R series, the lesser known "offset cab" versions known as the DM and U series, and also the Cabover version of the R series, the F series, all of which started production in the mid-late 1960s and (in the case of the R series) ended production in 2005, making it one of the longest produced designs in trucking history, much like the Kenworth W900 I have a few folders full of "specification sheets" for a number of them but sadly they aren't properly scanned so its a bit fuzzy, but a lot of info can be gained from them such as the Dimensions, engine types, transmissions, and suspension types here are some examples taken from the spec sheets (though take the image of the trucks with a pinch of salt, as often times they reused the same pictures for completely unrelated trucks to save money on printing)
I personally love the Mack R Series and would love to see it in Beamng, I wish I was good a blender then I would try to make it
