Specs; Stock '87 L98, swapped in a ~02 4L60e, stock 9 bolt, stock drive shaft

I recently swapped in 4l60e (from a truck) and as I am finishing up the small things went to install my stock driveshaft. All my research led me to believe that it should fit with no modifications needed. However with the car on jack stands and the rear suspension at full droop the stock shaft just barely fits. I had to give it a few bumps with my hand maybe 1/4" so it would fit. I can bolt the shaft in but am worried about at ride height the shaft bottoming out or causing damage. What's confusing to me is the slip yoke is not bottomed out in the transmission and looks to have room to slide further in.

Do the truck 4l60's have a shorter slip yoke or a shorter output shaft than F-body 700r4/4L660's?

Thanks

 

U have to have some slack for driveshaft movement or u will most certainly break something, seriously. U need to measure the correct length. U may be able to shorten your current shaft. Do it right the 1st time; a lot cheaper. Good luck.
Check youtube as to how to measure for a driveshaft