I did check the Tiagra a lot more tonight and I think I might have to cancel my order for the derailleurs, they might not work at all. The 4700 tiagra der I do have, like several other random, more modern ders, has an offset to the front and rear plates that would not allow plates to be screwed together at an alternate location like an older style might. However the plates, in part due to thickness and in part due to shaping are incredibly stiff compared to a number of older ders that I have. Makes me wonder if just cutting and shaping wouldn't have enough stiffness. The back plate has two widely spaced connection points plenty of shaping to make it stiff for pushing and the front plate is pulling where it is strongest. I'd suspect the upshift would be where it might have the most trouble and if Gavenelle doesn't come up with more shifters I might have to test out the new disc sander and the grinder and find out just how stiff the der is without the sides connected.