ORIGINAL: pimmnz
If you look very carefully at the muffler you can see the cooling fins along the top of the straight section. It all looks like an OS item.
Evan, WB #12.
What appears to be cooling fins is a reflection off the smooth surface. At first I thought it was fins too.
Thanks for all the replies and give Bo and Ray a big round of applause for confirming the Sun Ray was equipped with an HP 61 engine!
Mike