Hi! I got a sbc 383 with a procharger, i need a new transmisson and drivetrain, i guess a th700 original driveshaft and a 10 bolt dosent last long.. What do you recomend ? th400 + 12 bolt?

A 700r4 can be made to take the pain of that unless you're talking something like an f-1 or larger procharger. For the axle, just anything common should be fine being the 12 bolts, ford 9", or the dana 60. I'd go for the th400 if it's pretty much a drag car. I wouldn't use anything without an overdrive or lock-up converter if you intend on using it on the streets. Seems like there are an increasing number of cars using the 4l80e tranny with a valvebody that doesn't need computer control.

Are there any physical size differences between the 4L60E and the 4L80E? I've been looking into options for my build as well.

I'm pretty sure there is a size difference, but how much and where I don't know. I may be finding out sometime this year if my buddy gets his wrecked truck back from insureance so I can buy the motor and trans out of it.