The only customizing that I've done to date is paint mirrors silver or paint backup and other lights that needed color. Oh, yeah, I took apart a police cruiser to see whether I could add LEDs and now I can't get it back together :-}. I guess that was a "modification" of sorts. 
Just got a new PC and my data on things like the model year or variants are in a file on the old box. Here's the information that I had on hand.
At the Tomlinson Run Railroad, it's all about the food, so let's start there. [year? Grumman?] Charles Chips delivery van, 2002? Mercedes Ice Cream Van, and a 1953 Chevy Ice Cream Truck:
Then there are the non-perishable deliveries -- 1955 Chevy Step-side REA truck, [generic date] Grumman U.S. Postal Service delivery truck, and a 1965-2010 UPS delivery van, also Grumman or various:
The wreckers -- a 1953 Chevy Wrecker and a 1951 International Harvester Boom Truck:
General utility trucks -- 1956 Ford F-150, 1987 Dodge Ram, two (count 'em) 2002? Dodge Power Wagons (I think these were concept trucks), and a 2013 Ford F150-SVT Raptor with Super Crew cab:
Side shot of the same ...
Here is a rescue version of the 2013 Ford F-150 (on the left), and a "restored" 1955 Chevy Cameo pickup:
Google and Uber recently visited the Tomlinson Run Railroad and dropped off these self-driving/autonomous cars. Needless to say, the town folks are a bit concerned ... They are a 1938 Dirt Track racer (i.e., custom built), a 1940 Ford Standard Coupe, and a 1950 Nash Ambassador Hydromatic. Being self aware, I guess they could have introduced themselves:
Bringing the automomous autos up to the current era are these three -- also dropped off by McDonalds, Google, or Uber -- a 2002 996-Series Porsche 911 Carerra (1:48), a circa 2006 generic stock racer based on Ford GT40 and Charger components, and a 2017 CRS Sports Coupe:
Other automobiles, especially VWs and Fords, can be found on the carpet layout, but it's a bit too hot to unbox and photograph them at present.
Tomlinson Run Railroad
