Hi, I'm using Zen Cart 1.3.9h.

I'm changing how my shipping is set-up and I'd like to do the following:

USPS First class mail is free
USPS Priority Mail is a flat price
Fed-Ex 2 Day is a flat price
Fed-Ex overnight is a flat price

I currently use the USPS and FedEx shipping modules, but I don't think that will work with my new flat-rate pricing.

What's the best way of doing what I'm trying to do? Thanks.