2002 Jeep Liberty Helo

First, can you tell me what the vehicle is doing. It is uncommon for all of those parts to go bad at once. Also, the speedo problem is most lilkely a speed sensor problem, which may be contributing to other problems.

How bad is the differential leaking? It isn't uncommon for the seal to have a slight leak and then dust get on it and cause it to look bigger than it is. Have you had to refill the differential on a regular basis?

Finally, the likelyhood of all of the coils to go bad at once is very slim.

Let me know what is going on.