Questions about the infamous kw 8 bag suspensions

OHH #### so I just did a stretch on my k100 and its supposed to be off a 16 w900.How do I verify what model and year the cutoff came off of thanks in advance

 

Did you ever find out what was wrong with your truck I’ve had the same problem for long and still have a galloping truck

 

I did everything on mine
From front to back. the complete rear ends power divider, axle shafts swapped from ag200 to 400 conversion, hubs, rebuilt driveline and balance like 3 different times, carrier bearing(s) brand new drives month old now second set already in 3 years, new steers, 5th wheel, Still bounces. Only thing I have left is motor mounts and harmonic balancer. And maybe try different set of wheels and tires Then burn it to a crisp. I think
I’ve almost had enough. Lol