Need help ID ing Mcculloch motor. Mc100?

[ted johnson]

Scott, I had three 101A/A's, and all had a PTO side keyslot and RH threads. The 101B I bought for a buddy had no keyslot, and had LH threads. Did some A/A's have the LH threads? I bought all three of my A/A's at the same time in '73 from Brown Motorsports in Massachusetts. I had two as duals on my '73 Bug Stinger, and later as B Limited opens. Ted