I have a 4L80E and a car with an IRS. The rear differential is pretty much stationary, mounted to a cage which is mounted to the chasis. The 4L80E is off a 2001 2500 Series cargo van

What kind of yoke and driveshaft do I need? Do I need a driveshaft that has a telescoping yoke built in, or can I let the yoke float free on the output shaft of the transmission?

In a car with a floating rear axle, I guess the driveshaft relies heavily on it's ability to lengthen and shorten as the rear end travels up and down. However, in my car, the rear end really isn't supposed to move, so I am guessing the driveshaft is going to lengthen and shorten very little.

Thanks, -Dave

 

If you don't have a slip yoke in the transmission or a slip joint in the driveshaft, how do you intend to install it?

 

I think he's asking if he can use a standard drive shaft on the IRS. I think it would work fine. The trans yoke will slip into the trans and install as normal. The IRS center section should not move at all. Usually the yoke on the IRS is a flange style, so making a drive shaft to fit will be the challenge.

 

Yea, the yoke on the rear end is a flat 4-bolt flange. I think the driveshaft shop is going to use the flange off my old 2-piece shaft.

 

i would prob still want to use a front yoke that moves, for any flex in the frame-i cant remember what the vettes used, but pretty sure we had front slip yokes-i seem to remember sliding them in and bolting up the rear-most of the trucks used a 2 piece shafts, with the rear shaft sliding
in/out of the center support