Custom measure, does not contain "X" except before a cutoff number "X"

[sanalytics3]

Hello, I am hoping someone can help me with this question. I want to create two custom measures and/or table calculations to create two new columns in a dashboard.

1. Old car belt
2. New car belt

In custom fields I want to create two new columns, that will have a count of cars with the old belt and new belt. In order to do that, I first created two custom measures.

The old car belt equation or field I want defined as “Does not contain XX23 except for those before the serial number XX23556”

The new car belt equation or field I want defined as “DOES contain XX23 except for those before the serial number XX23556”

I know I could create a custom measure. And under field to measure, the serial number with measure type as count, name would be “Old car belt.”

Custom filter would be …

NOT contains (${cardata_cases.serialnumber}, “XX23”) 

HOWEVER I do not know how to calculate the addition parameter of “except for those before the serial number XX23556.

Ultimately I would like to show a stacked bar chart of car data count of cars with the new and old bar belt together.