Re: accounting . . .

to piggyback onto Earl's post, "rebuilds" where almost none of the original car remained were fairly common. The reason is the arcane accounting that inevitably develops in industries where rates are regulated in return for a guaranteed return. A car classified as "new" on the books would be depreciated over one period (say, 20 years), while a "rebuild" that was capitalized (carried on the balance sheet as an investment, as opposed to maintenance costs) might be depreciated over 5 years.
So some bright accountant figured out that basically scrapping a car, but reusing a few components (maybe trucks, or handrails, etc.) but most importantly, reusing the number, benefitted the railroad's bottom line.
This was fairly common between 1900 and the end of steam, and the same ruse was used on locomotives (D&RGW K37s and Reading T1s come to mind).
JAC