The 2 styles are also displayed in the News service bulletins by Chevrolet. The later style actually replaced the exhaust pipe, instead of wrapping around it, with a shroud that had the exhaust pipe inside it. The down side of these heaters were if there were any exhaust leaks present in the exhaust pipe inside the shroud, the CO exhaust would go directly into the passenger compartment.
Are your parts books for sale and do you know of any parts for either style...many thanks