53 card posted the information in a post about his mod.
Ordering information for the stack
Service Dept # (800) 963-0211 hrs 8am-6pm M-T 8am-5pm F EST
The lowes model number is 0190449
They said that they didn't' use the model number for the part but used the item description but here are both
Smoker Stack - 302-02009-00
On the assembly instructions its reference id is H
I found the price to be 15.98 delivered. The stack is a lowes master forge about 6 or seven inches tall.