Tring to remember but I'm sure even the naturally asperated engines got a cover over the mufflers. I know the turboed engines which don't have mufflers do have solid shielding all the way around complete exhaust system. This shielding was installed by company on all machines in the wheat belt. Any factory built machines as of approx '90 had the shielding. It provides an insulating layer of air between hot mufflers on NA machines and hot exhaust manifold and turbos on Turboed machines. Your R60 may note of been in the major problem areas so didn't get campaigned.