81-126 - are there any compatible, alternative rollers??

Thanks for posting, John. In general with sliding glass door rollers, it's always best to stick to an exact replacement, and it does look like the dimensions you cite are very close to what we list for the 81-126; just double-check to confirm. In this particular case though, there is one other roller we've been able to use as a replacement for this in the past: our 81-023. We've have used this one in the past to replace rollers like yours. However it's a bit involved, as you will need to remove the bottom rail on the glass door to install a 33-103 set screw. Take note you will need to use a drill and counter sink bit to install the 33-103 screw so that it lays flush in the bottom rail glass pocket.