Rear-end weight difference

70Valiant said

Charlie S is running a 7 1/4 with 3.91's and a sure grip, his 66 Barracuda with 170cid /6 on nitrus puts out 204 rear wheel HP and 355 foot pounds of torque. Your avarage 7 1/4 would blow appart on the first launch with that kind of power, his sure grip is where all of the strength comes from in his situation.

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I did swap out the 7 1/4 rear for a 8 3/4 in my Cuda. Low 13's in a 3250 lb car, is asking a bit much from the 7 1/4.
HOWEVER: it is now residing in my 66 Valiant. The first weekend out, it went a 13.928 at 91.91 mph at a weight of 2680 lbs.

This 7 1/4 is now in it's 5th race/street car, since 1974
I also have a 5.13 SG 7 1/4 and the parts to build another one with 4.56 SG.

PS: I would not run a 7 1/4 behind a hot slant with a stick. The 904 trans is a lot easier on the rear.