The name Planck was used in varies places as a substitue for Pleakenstalver.You would need to check on this a little further in your research.Here are some sites that will interest you in considering this thought that just maybe the Pleakenstalver's are associated with the Planck families.The actually name spelling for Pleakenstalver was Blickensderfer. Blickensderfer was used in Germany and Pleakenstalver was used as the English version.These sites or of most interest and it may shed some light on the Planck family. Try www.angelfire.com/md/forhissake/ancestry.html
Another will be www.corax.org/genealogy/history.html on this site please make sure you go into Phyllis Blickensderfer site. There will be a photo of Jacob Blickensderfer that will interest you. I found it to be quite interesting on all points that you would be looking for a Jacob C Planck but going on memory I believe the photo states Jacob Blickensderfer. I hope you find the links you have been looking for.
Some of the Pleakenstalver bunch was in Montegomery County for quite a few years. You could say at least 40 yrs or over. So I wish you all the luck in finding this link. Let me know what you find because I would be interested in finding links on some of our ancestors also. This could very well lead on to new avenues for sure on the Pleake/Plake/Pleakenstalver which is all names used instead of Blickensderfer. Theresa