Got a question on the center link for 98 S10 Blazer 4x4; is it the same bar/link as a 2wd?

 

No. It is different between the two. The 2wd centerline has the outer tie-rods mounting inboard of the idler & pitman arm mounting points while the 4wd has them outboard.

Here are some illustrations that will help -->
2wd Steering - Compnine.com
4wd Steering - Compnine.com

 

Got it. Would it be safe to say then that the need to replace a center link for a 4x4 is minimal. I have been advised to change the pitman and idler arm but was wondering if changing the center link would also be wise.

 

Dependant upon the mileage of the unit in question:this is a GOOD idea-The reason is that once you pull the tires and the centerlink-you have immediate access to both!
Do It!