I see all my fellow Ford owners have already tried to convert you. GRIN
So I'll just answer your question.
Last model year Chevy chassis was 1998
No 1999 Model year chassis with GM drive train.
Workhorse started building with their 2000 model year chassis.
Workhorse designed a new "W" series chassis with 8.1/Allison engine/transmission package and "I" beam front axle for their new 2000 model year chassis.
Workhorse did continue to build the "P" chassis with 7.4/GM tranny and independent suspension for a few years.
Richard
