-800s don't have the engine mount issues -900s do; so on my -800, I am going with OEM. They lasted 200k the first time, no reason to suspect they won't do it again

 

I’m probably going with the h3 mount because I only need the drivers side replaced. I got my wedding coming up in July so I gotta watch the Pennies. If it goes out I will go with poly atomics

 

just put the Atomics in while you are already there

 

i've been on AFP poly mounts since 12/20 and i can't complain. It's my daily driver, slight vibration in idle waiting on the traffic light to change. But doesn't bother me, beats replacing them constantly for failed OEM mounts

 

Anyone know why the H3 mounts would be different, well as far as the actual mount goes since I know the bolt holes and sheet metal be bent different? But what fails on them is the polymer cracks and fatigues from what it looks like. I looked it up and the 5.3 H3 mounts are that PN that was listed and they are almost twice as much haha.

My guess is maybe the H3 didn't have to meet the same safety standard and maybe has a stronger polymer (rubber), I think the GMT-900s are probably so weak because they are designed to shear off easily in the event of a crash and direct the motor and transmission under the firewall. I know the GMT-800 Duramax motor mounts did the same thing as the gas GMT-900s.

 

The Hummer mounts are solid rubber, the 900 mounts are fluid filled tor vibration dampening.