I'm having issuse connect the steering shaft on to the rack and pinion. It's lines up and starts to slide into it but then won't go in any futher.

 

Use a bigger hammer.

And here is one of the problems with this forum - they've been making the Impala for over 50 years! What year is yours?
Can you upload a pic?
Everything is clean and free of burs?

These questions may not help me to help you, but may help someone else to help you.