I'm afraid I need the list's expertise. I recently purchased an OMI GP40X and intend to convert it to one of CPR's 4500-series rebuilt GP38-2s. The problem is that the UP GP40Xs (including my model) had unique sideframes and the CPR rebuilds use good old fashioned Blomberg sideframes. I have been hunting high and low for a set of OMI blomberg sideframes, but so far to no avail. Have any of you had any success using plastic sideframes on a brass model? If so, which ones? I would imagine the mounting system would be completely different...any suggestions how to get aorund this?