This topic is very important for modders, we have 737-600 and 737-800s only and -600s are not popular anymore only few airlines left it in service!
-700 is a lot more popular, and also 737-900 theese planes would be a great addition to game as 737-900 is just extending fuselage and adding other door at middle (some more stuff engines I think), but 737-700 is just shortened 737-800s Why not implement that together with first large aircraft or multiple floors.
Also 737-500 not a bad idea, but that’s that! Hopefully you guys read this and implement, as it’s getting boring and more boring seeing same planes in your airlines and making unrealistic fleets. Thank you
P.S maybe also a lil aircraft modding
PHOTOS for REFERENCE :
maybe also 737-500