Im tearing apart my "91 4.0 and these are the main bearing I pulled out. Theyre main bearing 1-7 going from left to right.
My question is why is the #3 main bearing look different from the others? Is this how they come from the factory? Or was it replaced some where down the line.
Am I right calling these the main bearings? What are they called

 

Thrust

 

That is the thrust bearing. It keeps the end play of the crank in spec.

 

does the "thrust" bearing always go in the third main?

 

Depends on the engine. I normally see them on the rear main, but that's Chevy.

 

Do main bearing sets usually come with the thrust bearing or is that something I have to order seperate?
Are there any specific brand main bearing sets that are better than others? I want the best quality and most reliable I can get.

 

Main bearings normally come in complete sets for whatever under size you need. Federal Mogul is a good bearing maker along with a few others.

 

Come as a set. Get the numbers off the ones you have. It would be nice to see the crankshaft side of those bearings.