I know the 350 had a 9 inch tail and the 400 has a 4 inch tail. My question is how long of a DS should I order to go 400 to a 9 inch? I know the 400 has a larger spline but I'd like to get the DS on order while I swap the trans. I know there are a lot of people running a 400 to 9. What length DS are you running? Thanks for any help

 

Tolerances stack up and choosing a general length might or might not work, I would measure since its a small window to get it right

 

I understand that but this is a combo that is in thousands of cars. I'm sure it is a pretty common size. Just wondering if anyone knows the standard

 

I know you want it quickly, but when you measure for driveshaft length you want 1" of clearance between the output shaft end and the inside of the DS yoke to allow for proper suspension movement..

If you use someone else's measurement it would have to be with the someone with the same crossmember, trans mount bushing, rear end, rear end pinion yoke, lower control arms, and they would have to have similar springs and you would have to weigh the same weight as the guy who's measurement your using, lol..

There's a reason DS companies specifically say to measure your own setup, if the clearance is less than 1" then under acceleration you will bottom out in the trans causing major damage.. Too little clearance and you will have a wobble ride like a model T going down the road..

Just something to think about

 

I would say 6 9/16'' shorter.
http://www.transmissioncenter.net/Tr...asurements.htm

 

I appreciate your advice and link. Looking at the link wouldn't it have to be 2 1/4 inch longer.

 

You're right, I was looking at trans mounts for some reason.

 

Sorry, there is no standard, like it or not you should measure, the DS companies will build off what you send them, if it is off, it is still yours. More bad news, you need to have the car at ride height, and not on jack stands, with the suspension hanging you will get an incorrect measurement. This is where a 4-post lift comes into play...

 

as stated, meas. twice and cut once, lol
even bet 2 identical cars there could be diffs.
yokes come in 1310, 1330, 1350, they will make a diff in length
do it right, meas. with the rear axle loaded, unloaded (hanging)
I tend to fit them up tight, and who ever builds mine I double ck their meas. before I leave with the new shaft
not the answer you want, but the answer you need