351 Guys What Transmission?

The trans guys want to make money off of you...yeah the t56 is a killer tranny and you would love it with those 4:10 gears because 6 gear would still be a great highway gear. However, I make more than 500 to the wheels and my Tremec 3550 has lasted many years. Couple things to consider though...my car is a street/strip car and I only rack up around 3k-4k miles a year. I do not run slicks at the track, and to be honest, I rairly rev my motor past 6k rpms when on the street. You never mentioned what you're doing with the car...street? Race? Both? My friend just blew his t56 in his STOCK 04 cobra because he beats that car like nobody's business so any tranny can be blown if you beat it hard enough. I think any Tremec or TKO 500/600 will suit you fine, but it truely depends on how you treat it. On the opposite spectrum, a guy in my club has been running a factory T-5 for years while making 400hp with a blown 306, however he runs street tires, never races it, and treats the car very well while still having mad fun...just depends on what you're doing with the car...also, 500 crank hp seems rather low for a 408cid with a 6800rpm redline? 6800 rpms is pretty high for a stroked 408...solid cam?

Call either Liberty or Promotion. Both of these guys offer upgrades to the TKO that will allow it to shift over 7000. I believe ProMotion has a $150 dollar upgrade they call ensure shift that might do the trick. Liberty is famous for "faceplating" the TKO which is what the NMRA guys use, but I think it's about 700 bucks. I'd call both and get the scoop just to be sure.

if your building a drag car then you should be looking at an auto, if your building a street car thats going to go to the track once and a while then I would go with a TKO or T56