Definitely worth following up. CDY is so volatile, some people even ignore it. YCAII and 511 are not usually grouped among the "fast" markers. The "slop factor" in terms of number of generations is so great, calculating it is pretty much a waste of time, IMO. I prefer to think in terms of whether the match could or could not be within "genealogical time." With a GD of four, it probably is, especially if you have the same surname. This page gives a realistic, practical appraisal: http://www.familytreedna.com/genetic-distance-markers.aspx?testtype=67 Diana > From: hessen4 > Sent: Wednesday, January 19, 2011 12:50 PM > > I have a 63/67 match we differ as follows; > on YCA IIa 23/24 , on CDYa 36/37, on CDYb 39/38 , 511 11/10 > > Is this a match which I should follow up on? > Are these markers fast or slow markers/ > What would you guess the number of generations back to a common > ancestor be?

I thought I would pass on my results from upgrading from 37 to 67 markers. I had (and still have) as a projected R1b1b2 no 12 marker matches, one 23/25 with another surname that falls away at 37 markers, and no 37 marker matches. It was suggested on the list that (as I know) that sometimes matches might not appear at lower levels, but appear at a higher number of markers. I just received my results for 67 markers, and I have one 60/67 with another surname on FTDNA. At ysaerch I have two 61/67 and one 60/67 with that surname. I think I come from a long line of just having enough males in each generation to keep the line from daughtering out. FMUDM on ysearch Rick Saunders