If you can't stand a 350 Turbo, then go to the 400. I honestly don't understand all the hype about the 700R4 all over the perfomance mags today. The shift quality in a stock 700R4 is dismal at best, and the things weigh a ton. I guess everybody loves that bitchin' low gear, it makes a 350 Chevy haul ass like a big block, but it's all over in 2nd. And, if you do manage to stay with a 5.0 Mustang through 2nd, you're going to see tailights when it goes to 3rd and slips into lockup. What crapola! 350 Turbos are better trannys than most people want to believe. I've overhauled about 40 of them over the years, and only had two that were beyond salvation. They can handle any smallblock, and with a good intermediate sprag clutch, they can tackle a big block as well. I can't deny that a 400 Turbo is GM's finest effort though; you cannot beat them for shift quality and durability. A 400 weighs about a ton as well, but in this case, it's worth it.

I'm not just blowin' smoke here, I'm driving a '90 Chevy 1/2 ton with a pretty tough 700R4 in it on a daily basis. For the most part, I don't use the overdrive unless I'm on the highway, since it's always shifting into it at exactly the wrong time. As a matter of fact, I generally shift this transmission manually every time I drive the truck. The thing just doesn't seem to know when to shift, so I do it for it. Low gear is a blast, but it's more or less useless for anything else than showing off. I much prefer the 350 Turbo in my '79 Chevy 1/2 ton, it knows exactly when to shift, and it has performed flawlessly since 1979 (26 years and counting) without any more than an occasional fluid and filter change.

I'd think very seriously about going to a 700R4, it's a lot of trouble and EXPENSE to go to for dubious benefit. And besides, how come GM couldn't even call this one a Turbo? Were they ashamed of the mess they made redesigning the 400 into an overdrive, and felt like it wasn't worthy of the Turbo lineage? That's kinda what I think, although I don't have an explanation for using Impala and Malibu for those atrocities that now bear those once proud names.