The J-L24-Y-DNA Project is for all haplotypes of J2a (M410+) which are derived for SNPs L24/L25 (J2a4h).
If you are tested or estimated as J2 or J2a and carry DYS450=9, or DYS450=10, then you are likely a member of the J-L24 clade. If in addition you carry DYS445=10 (+/-1) or DYS445=6 (+/-1) then you are very likely a member of J-L24. These are just estimates. One cannot be 100% certain without actually testing the L24 and L25 SNPs.
The SNP (mutation) rs35248080, assigned by FTDNA as L24, resides downstream of M410 (J2a), L26 (J2a4), and L27 (J2a4). The L26 and L27 SNPs replace the old condition DYS413 <= 18-18 (previously defining J2a4) as SNPs are pretty much unique (statistically invariant) whereas Y-STRs in general are not.
The SNP rs34534058, assigned as L25, resides downstream of L24. L25*=L25(xL70), the root of this clade, represents the majority of the cluster with the modal characteristic defined by DYS450=9 and DYS445=10. Also included within L25* is another group having DYS445=6.
L70 is a new SNP, currently not shown on your FTDNA Haplotree page, but it lies downstream of L25. Within L70 we find the main group of haplotypes represented by DYS450=9 and DYS445=6 as modal. The DYS445=6 deletion appears to have occurred in L25* before the L70 mutation. At this time no SNP has been found specifically related to the DYS445=6 deletion.
Within L70 there are 2 additional SNPs: M137, M318, defining subclades of L70. These appear to be relatively rarely occurring. Recently a group of Jewish Priests on the island of Djerba, Tunisia were found to be M318+. The project administrators will advise if they think you should test these SNPs.
With time, no doubt years of time, and enough members joining our group and testing SNPs and markers we hope to have the genetic structure and history of the J-L24 clade clearly established.
Useful websites to visit:
Z387 and J-L70 and DYS445=6 Map
Hullinger Y-DNA Blog
The J-L192.2 Map
Definition of terms in genetic genealogy
FTDNA Y-DNA J2 Tree
The ISOGG Y-Tree
DNA COLLECTION METHOD
Palindromic Region Map
DYS425 NULL Project