emd and ge have websites where they decribe the various engines they build, in detail… they begin with a basic engine at various power levels to which you can add anything you want: more capability for engine, cooling, braking… support: gadgets to alert the crew (and technicians) as to problems with any aspect of performance… advanced support monitors performance with radio-signals to nearby & corporate stations as to wear-and-tear issues and emergency status, which the crew also sees…
amenities such as a/c, microwave, toilet, icebox are optional on some new models, std. on others… noise (vibration) suppression is available, where the cab is insulated from components which create noise or vibration… noise pollution is a recognized aspect of industry safety nowadays, not just in politics…
most any feature available on new units can be retro-fitted to older ones… just calculate the necessity of the feature versus the remaining life & value of the eqpt… you can see immediately what you can’t afford now, and how long before a replacement is due which has the bells & whistles you’re praying for…