I’d say so. [*-)] The “NEW” date, when applied, should match the “BLT” date. If you take the “BLT” date to be correct, instead of “NEW 7-78”, it could read “BI 7-78”, indicating that the car was re-weighed at Blue Island Yard, in Chicago, in July of 1978. This was a Rock Island-owned scale, but the stencilling could also read, for example, “CB 7-78”. “CB” is Council Bluffs (Iowa), a Union Pacific-owned scale.
If you accept the “NEW” info as correct, the “BLT” date should also be 7-78. BLT refers to the date which the car was actually built and never changes unless the car is re-built, which is usually a major operation involving the car’s frame. Re-painting the car, changing the doors, or even the roof, for example, is not considered a re-build. In the case that a car’s frame is altered or replaced, it would get a new “BLT” date (or, sometimes, a “RE-BUILT” date), and would also be weighed, acquiring a “NEW” stencil with the appropriate date.
A good way to give your cars a bit of history, to go with the application of weathering, is to give them re-weigh (and re-pack) data. The car pictured below, a 50 ton PRR boxcar has a “BLT” date of July, 1934. It was re-weighed, as required, 30 months later, in January of 1937, at East Altoona, PA, and stencilled with that scale’s symbol, P57, and the date. Because the car’s “LT WT” had changed from what it was originally, the original weight was painted over and the new weight stencilled on. This also affected the LD LMT, as, for a 50 ton car, the total of the LT WT and the LD LMT must equal 169,000. Consequently, the figu