That 250 damper looks like a better design but the grooves are further apart than the 54-62 balancer that the bracket maker (Davis Speed) said to use.

I had an 03 GMC/Isuzu box truck that also had hydraulic/electric. I had to rebuild the brakes and the parts cost a fortune. I think one rear drum was over $400. I think they use hydraulic/electric so you don't need a CDL. Air brake parts are cheaper but I don't have a CDL.