If I take the injectors out of the manifold, do I need to replace O rings?

 

You might as well. There are kits for them, O rings and other parts, for about $1.80 - $3.50 each at your local parts chain store. The higher price is for Beck-Arnley parts. As near as I can tell it's the same quality at a higher price.

-Joel.

 

I don't think it is an absolute requirement. Just be carefull with the process, and lube them with ATF when you put them back in.