Tube from exhaust manifold to intake horn

[Bryan98801]

'76 C10 with the 350

I've heard it called a heat riser or a preheater hose. But the tube from the heat shield on the right exhaust manifold to the bottom of the intake horn. What did you use for this? The one on the GM engine in my Jeep is stamped/crimped sheetmetal. What is the one for the 350? And where would I get something like it? I've checked all the parts places online and all they have are the generic dryer duct looking things.

I'm pretty sure this is the reason my truck is so cold blooded. (doesn't like to stay running at first startup) Any other ideas would be greatly appreciated.