Quote Originally Posted by 85chevyk30 View Post
The duramax motor is a 01. I have talked to these guys at www.transmissoncenter.net and they swear they can build a 4l80e to handle 1200 horsepower. My duramax is goin to have 20 over injectors and 2.6 bd turbo.

Those guys don't exactly have a good reputation for building what they advertise, many an unhappy customer with them in the diesel world. A 4L80E will surviv in a car in 1st-3rd, but WILL self destruct in 4th if you give it any power. The guy in ORLANDO FL with the 9 second quarter mile DURAMAX MUSTANG is running a 4L80E tranny, but even he will admit that it cannot hold in OD for anything more than steady cruising. The BUICK GRAND NATIONAL with a DURAMAX is backed by a 4L85E built my MIKE L., but you won't catch him in OD doing anything more than steady cruising. In a truck at even stock power levels the 4L80E will NOT hold, and even with a full on build capable of holding 1200HP it won't take more than about 500 torque in OD which a DURAMAX will make stock no problems.

It's your money, but I would strongly caution against it. You already have the HD truck, why not give it a true HD driveline. I know lotsofmiles(a member on McRats forum) has a DURAMAX van and can obliterate a 4L80E with just tuning in his LLY van and is currently in the process of swapping in an 06 ALLISON as he is tired of tranny problems. And I know pussow(the guy on EBAY who sells the conversion CD on EBAY) also got rid of his 4L80E as it couldn't hold up to his 06 van motor(250HP version). Just remember this when you make your decision, most tranny shops advertise HP numbers that there tranny can hold. But who cares? It's a diesel, so torque is the number you have to concern yourself with. Hence why a 700R4 can be built up to hold up to some pretty high HP small block chevies(550HP+), but even a stock 165HP 6.2L will eventually kill it even built.