Gmc Savana G1500 1997

[chevy350]

I have a GMC Savana G1500 (1997), which has a Chevy 350 V8 5.7L motor.

 

The motor which I have on the car broke down and I'm looking for a new one.

 

Is there a place you can refer me to, where I could buy such a thing? Also, what is the

 

difference between a motor block with 4 and 2 bolts?

 

Does anyone have an idea whether I can fit 5.3L motor, which is meant for models after 2003 on a 1997 Savana?

 

NB! I'm from Estonia, not from the US.