The L2 L4 injuries are most commonly caused by Backpackers and Military packs , and with the load we carry now days , any back injury is almost in every case is No-Go , alot would also depend on you previous discharge , as you never stated any reason as to why you were discharged. That would factor in alot , since if they have to work say 10-12 hours on getting you in and a normal enlistee takes say 2 hours why would they take all the time for a case that is not certain .
Be prepaired to write out a letter to the MEPS CO explaining why you got discharged and why you want back in , and don't BS them will the usual crap they read right thru that.
And how many different places are you ging to post this?

USMC 1982-1988

....US Army 2006- TBA......
Still a Marine now just on vacation in the Army .