Driveshaft length

[Sean80monte]

Hello, new here. I have a 80 Monte Carlo that I swapped a 87 grand national rear end into. Does the driveshaft from the 7.5" rear end fit properly? It's installed and runs and drives but am concerned that's it's gonna break the transmission. I've read that it needs to be shortened. I attached a picture of the driveshaft in the transmission while on pavement. Thanks for your help.

 

[Blake442]

Driveshaft needs to be shortened 1 inch.
Might as well throw a new seal on the tail shaft since it's likely already been wiped out...

 

[Sean80monte]

Thanks for info. I'll get it out and get it to the driveshaft shop this week.

 

[pontiacgp]

I would stop driving the car, when the rear suspension compresses the driveshaft could crack the transmission housing

 

[Sean80monte]

I've actually only driven it 4-5 miles total since I changed the rear end. Thanks for the advice.

 

[pontiacgp]

when you get the driveshaft shortened depending on the condition of the tube you might want to ask about a new tube. It should only be about $50 for a new tube since you have the yokes and the shaft has to be balanced after it is cut. Also once it is balanced permanently mark the position of the slip yoke cause it is balanced with the driveshaft. If the u-joint is ever changed and the slip yoke is put on out of phase that could cause a viabration