If you can rebuild the knee action shocks, they will work just as well as the later tube shocks.
This is due to the fact that the tube shocks used on these leaf spring trucks don't do much to improve the ride anyway.
I suppose they may help a little bit. I had the lower tube shock bolt fall out on one side in the rear, leaving it hanging freely, but did not notice any difference in ride quality before or after replacing the lost bolt.
