There is a lot of reading available at NHTSA website regarding Workhorse brake issues related to model years 2002, 2003, 2004 and 2005 on the W20 and W22 chassis. Here is a summary of the number of complaints filed that fall under ‘service brakes’ in relation to the total complaints filed for that specific model year and chassis.
2002 W20:
3 out of 3 complaints filed were brake-related
2002 W22:
16 out of 23 complaints filed were brake-related
2003 W20:
9 out of 9 complaints filed were brake-related
2003 W22:
31 out of 32 complaints filed were brake-related
2004 W20:
8 out of 9 complaints filed were brake-related
2004 W22:
21 out of 26 complaints filed were brake-related
2005 W20:
1 out of 2 complaints filed were brake-related
(2nd one was brake-related, but complaint was regarding the 'parking brake')
3 out of 3 complaints filed were brake-related
You can search and then review/read the complaints at
http://www-odi.nhtsa.dot.gov/complaints/ and make your own conclusions as to IF a problem exists.