I will echo JohnD's comments above about the threading. I recall the shop crank pullers came in two pieces. It had a center push rod that was threaded with a 15 or 17 mm head. The barreled body was threaded on two ends. One end was for most cranks of the ISO/JIS variety. The other end was for odd-balls. We'd unscrew the center push rod out all the way, and flip the outer barrel to find the right threading, and I believe we had several tools with different sizes.