SoCalMan,

Jerry should be the one to answer your question, but I haven't seen him on the board in the last week or so, so I will give you a reson for the difference, but my answer is definitely the "unofficial" answer!

The ground loss calculations are different. The distances apart at the finish are fixed, but the "sheets" figures also take into consideration ground loss and weight carried. Presumably, T-Graph and Ragozin use a similar formula for weight carried (although I don't know this to be true), but their ground loss adjustments can certainly vary and I guess they do.