I want to step it up a little.

[Pont406]

Current set up runs 8.6 in a 1/8 mile at 80mph. Using formula conversion it's 13.5 in a 1/4 mile. i want to step it up some. Short block is done with a mild hyg roller, waiting on heads from machine shop. Looking at about 430 hp at the wheels and 415-420 toqrue. Everything else will stay the same but a converter. Last time out trans started puking a little after 8 back to back passes but still ran ok.How durable are stock driveshatfs and stock rebuilt th400? I am trying to get it done with left over parts laying around.

[Jofin66GTO]

I think you would shatter u joints before twisting the driveshaft. There was a forum on here I was reading the other day about th400 vs th350. I would google again to be sure but think stock th400 can handle over 500hp and torque. If I'm wrong let me know cause I'm also running th400 and doing a build soon.
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[Street Smart]

There are a couple of up grades that should be done to a T400, extra clutches, better sprag, etc, but even bone stock it should hold up fine.
430 hp at the wheels should put you in the 11`s(1/4mile). is that a pontiac motor?