I am having a complete system installed (have baseboard heat now). Original invoice for installation was for a Trane 4TWX6036B1 and a 4TEE3F40B1, upon delivery and beginning the installation the air handler has changed to a 4TEE3F39A1. There are telling me this is a better unit and cost more than the one on my original order so I am coming out ahead (these kinds of statements make me wonder if it is true). Is the 4TEE3F39A1 better than the 4TEE3F40B1? The unit will be installed in the garage and supplying air through the attic to each room. The numbers I can find lend to the original invoice as a better choice, as far as price I cannot find anything that list the 4TEE3F40B1 being cheaper that the 4TEE3F39A1, is it cheaper? Any help appreciated.