You might be able to use your bellhousing
and a adapter plate to match up with the T-5.
If your 390 is modified i would think about
other transmission like the tremec 3550 or TKO. The T-5 is rate for 300lbs to 330lbs
depending on model you get. The 1990 and
newer are the stronger type. I would call
Mustangs Plus or
www.windsor-fox.com for
info about trans adapters.
Regards,
BillGear
www.289mustang.com