im going with a th350 trans that should be here in a couple weeks

my question is my driveshaft...do i have to get a custom driveshaft made or will the factory one work?
anyone swapped their 4l60e for a th350 in here?

 

The driveshaft will need to be longer for the TH350 so you will have to have one made, or find a used one that is the correct length.

 

you have an idea of how long it needs to be?

 

Tranny questions belong on "Drivetrain", not "LT1 Engine Tech", which you appear to be aware of, since you posted it on both forums. Please do not post tranny questions here.