Hey ill be fitting my splits soon, Just wondering if the door speaker in a TH Altera LS (6 speaker) is a full range speaker of just a mid range or low range. the reason is i want to know if i can use the exisiting Cable going into the door to run into the crossover to run my splits. If it only does low range there must be a factory crossover somewhere that i will need to find first.

Does anyone know?

i'm 99% sure the speaker is full range, and the dash tweeter has a built-in crossover removing low frequencies.

yep full range.
Tweeter is highpassed using a simple cap.(at the tweeter)

You will need to unplug the tweeter probably, otherwise you will have two tweeters playing (one of which is a stock so will likely reduce your sound quality)

The wire running into the door is fine to run your splits.

cool thanks guys :)