My friend and I stuck my converter on today so we assembled the tranny and motor (4L60e and a 4.8) and started to stick it in the Grand National but it looks like the stock driveshaft (1987 GN) is too long.

We have a motor mount issue right now (put the plates on correctly but still seems flipped as it would set back so far we couldn't get it in without pounding the firewall to clear the head) so don't know if that is the issue or not but figured it couldn't hurt to ask...

Are you guys using stock G-Body driveshafts with LS drive trains?

 

Doubtful. Your going to have to measure and call someone like PST. Or Jameel said he has a driveshaft guy that comes out and measures for you. How long is the stock one? F-Body is 41" iirc.

 

I swear I read people using the stock one though... Doesn't matter how long it is, has to do with where the drivetrain sits now.

 

Have to get the original drive shaft shortened and balanced. Or go with a whole new drive shaft.

 

Huh? I was just saying measure it and depending on length see if a F-Body one would work. Gil has 3 sitting in the garage. Or if you could cut down an aluminum one and rebalance it.

 

Pretty sure GN and F are both 51"...

 

I used Dennys driveshafts for mine... But food for thought a 4l60 should be the same length as a 700R4 which I believe is around 3in longer transmission then the stock 2004R...

And you shouldn't have to pound on the firewall either, I am running 1in setback motor mounts with stock clamshell mounts attached and have plenty of clearance.

 

Stock F-Body are between 41-42". If GN is 51" it won't be even close. Just measure. Best bet is to get one made unless you know of a good driveshaft shop local to shorten yours. 3" chromoly are like $400 new. Aluminum a little more expensive.

 

For a performance car it is well worthwhile to get one made that is larger diameter and high speed balanced. RPMs and stock don't mix well, especially on a stock one that is been cut and re-welded

I got mine from Bleaumenthal's manufacturing in OKC. 56" chromoly steel with solid u joints, 3.5" diameter high speed balanced. Was $230 shipped to my door.