Hey guys i have a possible issue with a np149 from a customers silverado ss truck. I just rebuilt him a really nice 4l60e after he broke the splines out of the input drum. Once I installed trans and bolted tfcase up I noticed tht with the trans in park I could still spin the rear/front driveshaft. I verified trans is in park!! Pulled tfcase and trans is definately going into park. Tfcase is splined onto rear output shaft as well.

So i tore tfcase down and dont see nothing broken tht connnects the input to rear output. Only thing i see tht could be the culprit is the viscous coupler. Is this likely???

With the outout shaft mounted into a vise (on input side) i assembled everything up to the chain drive sprocket for the front. With the ouput shaft held in vise i can spin the viscous coupler and everything above it. So this leads me to believe its bad but im not certain. Honestly dont fully understand how tht coupler works lol.

First ive ran into this issue! Any help is greatly appreciated thanks.

 

Yes, since the 149 Transfer-Case (New Process Gear/ New Venture Gear/ Chrysler+GM) is only a single speed unit (No 4-Wheel LOW) and is a "Full-Time" All-Wheel Drive unit...

A viscous-coupling that is no longer operating properly... will prevent engine power from passing through the transmission output/ transfer-case input, and getting to the drive-shafts and differentials (front and rear).
Sorry it took me so long to see this and reply.

On another note, to all here...
My apologizes for not being on the forum for the last 2 - 3 weeks.
I have suffered a major medical incident; and I am now starting to recover.