1/ If your Difficulty / Terrain grid had each of the appropriate 25 combinations of 1, 1½, 2, 2½, and 3 for Difficulty and Terrain covered a minimum of 3 (THREE) caches per square when posted for the 3x3 Challenge then there is no need to repost it. BUT, for this Challenge you need to have found a minimum of 75 caches, with 3 in each of those squares. I know we are a bit light-on with some of those combinations in the local area, so I am indirectly encouraging a few more of the challenging caches to be placed. Or, you need to go further afield to fill up the required numbers.
My, Grahame Cookie's Grid @23/7/12
2/ As part of the Challenge you also need to post with your Found log 3 caches (on GC) of different Types (Traditional, Multi, Unknown, Events, etc) that were found in the same day, give their GC codes, and the Date that you found the three.
3/ Part 3 of the Challenge is to found 3 different Sizes of geocaches found in one day - eg Micro, Small, Regular, Large, etc. (It is possible that the same caches used for Types fulfill these requirements). List the GC codes, Size, and the date that you found the 3 different sizes. Otherwise, you may use a Public Bookmark to highlight the appropriate caches and give it as a link in your log.
Use the same access track as for the 3x3 Challenge. A 4wd would be handy, but I got there in my Mazda Metro; I just wouldn't trust it in the wet!