Exploding Torqueflites

I Have A 72 Dart That Run 6.90s In 1/8 Mi. 1.46 60 Ft. Times, About 6 Weeks Ago I Broke A Rear U Jt. On Staring Line. When I Bought Car I Didn't Ck U Jts, They Were Jts, With Greece Zerks, They Are Hollow, And Weeker Than Sold Jts, I Put A New Joint In Rear And Didn't Ck Trans For Damage Went Back To Track Made 6 More Runs Noticed A Trans Leak, Thank God I Then Checked Trans It Was Cracked All The Way Around The Frt Of Pump . Only 2 Inces Remained In Tack. Could Of Realey Done Some Serious Damage To Car And Myself. Replaced Case. And Went To Aluim Drive Shaft With Solid Brut Jts. I Had The Local Performance Trans Man Change Case And Check All Parts . So Check Ck Trans Often. My Trans Is A 904 They Are About 80 Lbs Lighter Than 727. If Built Right They Can Handle 5 To 600 Hp. If You Use A 998 Or 999 Case They Are Stroger Yet, And Have A Extra Clutch Plt And Wider Band. Good Luck Gary!