Easiest swap from TH400?

[Funkatation]

I'd like an overdrive transmission.. whats the easier swap? 700R4 or 4L80e? This is in regards to changing drivetrain components.  I'm leaning towards a 4L80e because I'm building a 489...

[Irish_Alley]

the 4l80e needs a tcu that is the major hang up with them but it should be around 500 if not cheaper for one and they can hold if memory serves me right 400hp. much stronger than the 700 

[Funkatation]

Does 4L80 require any driveshaft changes?

[Irish_Alley]

yes it is longer than the th400 so the driveshaft will have to be shortened

[Irish_Alley]

the th400 could be
29"
34"
or
38"

the 4l80e is 32.5"

i dont know if you can find a 91+ chevy long bed with the 4l80e and bed size of yours and take the trans and driveshaft out of it and be done.

theres something about the 91-93 chevys with the diesel that you can take the tcu out and adapt it to a gas motor and be good. but i have one cause i heard about it but i cant seam to find any information about how to use it on my cummins

[Irish_Alley]

i forgot, on my 91 i havnt set up atcu to make it automatic but im driving it with the "black box" from jakes performance for $200. i love it but i still want it to be automatic and with this box i can simply unplug it and plug in the tcu and its now automatic.

[Funkatation]

Does the 700r4 require any driveshaft modifications to work? I've seen a stage 4 for sale locally around here, it's a bit more than 4L80e, but if it's cheaper to put in and doesn't require electronics I may consider it.

[Irish_Alley]

think the 700 is about 30"

[Irish_Alley]

but its a 27 spline output shaft so you will need a new/used yoke and you will have to deal the with the tv cable and torque converter lock up. 

[Irish_Alley]

this should help out a lot
http://67-72chevytrucks.com/vboard/showthread.php?t=574800

[Captkaos]

The easiest swap for the least amount of money would be the 700R4 but you will want it built to handle whatever you are building.
You didn't say if you have a 4x4 or 2WD so that would complicate things also.  Regardless.  going to OD trans will require you to change the driveshaft on a 2WD.

[Funkatation]

Its 2WD. Still mulling my options.  If I go 4L80e, I think I'd rather change out the gauges instead of spending 300 to convert to mechanical speedo.  Mines off any way and I read that electrical ones are easier to adjust.  Just means more money!