If you're looking for gas, try to stay above 1999. If it's a Ford make sure that the engine is the 362HP V10. Ford had all the issues resolved by that time. You could have some ride/suspension issues with the F53 chassis, but the folks here can help with the least expensive fixes.
If it's a Workhorse chassis, they had some serious brake issues that should have been fixed in a recall. The WH also had a recall on a clip on the fuel system that must be taken care of. The issue with a Workhorse chassis is that the engine and chassis are no longer in production. Consequently parts could be an issue at some point in the future. I had a 2005 WH and dearly loved it.
Good luck on your search.
