I found this info, about the three matching Sayre Built Well Cars, and a single photo of one of them. No further info, on the 9955, which I was wondering about.
There were plans and a photo of an LV well hole car in the 1922 Cyc. The plan showed a car that was 55 ft. 10 ins. long, riding on 6-wheel trucks. This car was basically a fishbelly side sill flat with a hole in the center, 26 ft. 2 ins. long by 6 ft. 1 in. wide. The plan showed a wood deck, but the photo showed a steel deck. The sill at the ends was a foot thick, and 23 inches deep at the center.
In 1949, there were three cars in the series 9951-9953. The cars were rated at 110 tons. The LV destroyed these cars in 1956.
Lehigh Valley 9955 well center flat-car built in 1958. This was much different than the earlier cars. This LV car, no. 9955, was the only one. It rode on 28 inch diameter wheels. Disposition unknown, regarding it.