I've chosen these, but have yet to successfully order them:
Motor mount [Hummer H3 solid rubber] (2): 25847739
Trans mount [GMC Yukon Denali AWD] (1): 15840278
The trans mount is no problem; stock part for my vehicle. The Hummer mounts are "on national backorder" with GM according to the sites I've used. They WILL NOT take an order without a valid VIN. Turns out, that part number is for one side (forget which). So even finding a valid VIN for a Hummer H3 gets flagged, because to them I'm ordering one of them wrong. I guess I could place separate orders, or find a second Hummer VIN. I'm going to see if RockAuto or another generic parts house has these. I'll have to pay more, but at least I'll get the parts. Sheesh.
EDIT: generic parts houses I checked are all out of stock. I guess word has gotten out on how good the H3 mounts work. I hate being the last one standing when the music stops.