McCulloch Mc 91  ... 1966

Bore 2.165 ... Stroke 1.635 ... Displacement 6.06
Mc 91 Model 400165  10-
IPL No 84456 / 87697
Owners Manual 85205
Production Period 12/66 to 4/68
This block is a little rough but may help in identifying by the casting what your block may be.