Roar from underneath while driving...o

What is your question?

I've replaced the manual transmission with a T5. I've put in Dextron/Equiv. fluid in this, as it is the recommended trans. fluid for it according to my Haynes repair manual... I replaced the rear seal in the transmission, awhile back and checked the fluid level in it, added a qt and a half into it. Any reason for this to continue to roar?