If u take the cv part off the front drive shaft by the t-case can I put it on the rear drive shaft to make it longer?

 

Can you be more specific? Are you wanting to put the CV onto the rear shaft, or remove the CV from the front to use the front shaft on the rear? Either way, the answer is no The end of the shaft is different when a CV is being used. A CV will not go onto a shaft properly if it is not made for it, and a CV shaft cannot be used as a non-CV shaft.