"He who marches out of step hears another drum." ~ Ken Kesey
You could use rope (that doesn't stretch) to measure half accurately, then x2.
Call MR give them serial number... they will have exact belt specsSent from my iPhone using Tapatalk
From memory I think the belt length for a 8' heat chamber, 4'in and 4' out is 396" long. If you need a quote, let me know we sell them !