One other thing to keep in mind, look at the parts list for 6-18010 (PRR Scale turbine)
for example, the boiler front is listed as
6108010024 | BOILER FRONT / PRR SCALE TURBINE #6200 |
Ignore the third digit, 0 in this case so you can see how the 6-18010 figures into the PN.
The last 3 digits define the actual part, 024 in this case.