Looking for a Module or solution

[Guest]

I have some products that I ship UPS, and I have some products that ship via USPS but not both.

 

So I am looking for either a module that will know when I want to ship a product via UPS or USPS. Is there such a beast already?

 

Or can someone point me to the correct file that I can modify and with some suggestions to make the needed changes.

 

Basically the items I ship via USPS weigh less than a pound and I can ship via US Mail First Class. while everything else goes UPS and wiegh over 2 pounds.

 

I was thinking I could tell the program that if the products wieght is less than 1 pound only show USPS and if the product wieghs over 1 pound to only show UPS. However I have no clue where I would tell the program to do this.

 

Any help would be greatly appreciated.

Thanks