difficult swap??? what's different to worry about??

 

The computer for one thing, and I hear it's too big for the transmission tunnel.

 

A TH400 is a tight squeeze and a 4L80E is bigger. You could make it fit but it would mean cutting out the tunnel and fabricating a new larger one.

You would need an aftermarket stand-alone computer also to run the tranny. Companies like JET sell them.

From what I've heard, a rebuilt 4L80E (without the computer) is around $3500. I hope the one in my truck doesn't blow up.

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87 IROC-Z SuperPro ET Bracket Race Car
461 naturally aspirated Big Block

Best ET on a time slip: 11.242 altitude corrected to 10.89
Best MPH on a time slip: 121.52 altitude corrected to 125.89
Altitude corrected rear wheel HP: 497.9
Best 60 foot: 1.546

Racing at 3500 feet elevation but most race days it's over 5000 feet density altitude!
Member of the Calgary Drag Racing Association

87 IROC bracket car, 91 454SS daily driver, 95 Homebuilt Harley

 

well i saw one on i think it was yahoo classifieds in ohio for $500, unused. And I did read on an older post on here that you can get around the computer issues.

But i'm not about to cut up the tunnel, so screw that. I'll just rebuild my 700r4 to be a monster...

 

I don't how you can get around the computer. It controls everything about the tranny. Line pressures, shift points everything. It's a fantastic tranny if you want to spend the bucks on it. There's another valve body available that you can get that makes it into a 6 speed. It engages the OD between 1-2 and 2-3 to give the 2 extra gears. You can also buy a plug in shift programmer. 4 positions. Stock, Stage 1, Stage 2 and Race. It electronically holds the line pressures higher for more firmer shifts just like a shift kit would do. Drive to the track in stock. Race in "race" and drive home in stock.

For a street tranny it's good but it's just too big and heavy for a race tranny. I currently have a TH350 in the race car and want to go to a powerglide.