For something on the scale of the USPS fleet, economies of scale would come into play. If such vehicles were very highly modular, all of the modules could be re

For something on the scale of the USPS fleet, economies of scale would come into play. If such vehicles were very highly modular, all of the modules could be removed and placed into another frame and the old one recycled. (Come to think of it, this is also somewhat done with Abrams M1 tanks.)