I currently have a sd33na/727/3.73's with 33's . I have been kicking around the idea of upgrading to a SD33T/T19/D300 package. But I have also been looking into a swap to a different make package. Possibly a GM 6.5 turbo diesel. What have those of you that opted to replace the SD with a 7.3, 6.2, 6.5, 4BT, ect... Seen for mileage? Did you go with an auto trans or manual? Thanks in advance.