Chevrolet Repair: size of engine, chevy van, gas mileage

Question
I need to know the motor size of a 1990 Chevy Van 20...this is not a G20 ...just 20.  I can't tell if it is a 305 or a 350.  Can you tell me how to tell the difference?  Thank you.

Answer
A lot of difference between 305 and 350.  350 is more powerful, has more horse.  More of a work motor.  305 is a design for gas mileage and less horse power.  They look identical.  

A 20 and G20 are most likely the same thing.  You need to take your VIN and get the 8th digit.  That is the character that will give your motor size.  Any auto store should have this information from that digit.  You may find it online.