Correct operator model for awning windows

Looking for a RH awning window operator (at least I think these are called awning windows). My broken operator looks very much like 39-378 (though it also looks a lot like many others). The dimensions are: Distance between top and bottom mounting holes: 5 1/4 (dim a) Distance between bottom two mounting holes: 1 1/8 (dim b) Distance between pivot holes on swing arm: 2 1/2 (dim c) I think I can deal with a slight difference in dim b by drilling a new hole in the aluminum frame and using a bolt instead of sheet metal screw. I don't know if the difference between the 2 1/2 vs 2 7/16 on the swing arm is a "killer" or not. Or, if there is a model that has my exact dimensions that I missed. Thanks.

Thanks for the info, Dave. I notice that the 39-012 has an exact mounting hole dimension match, but the swing arm with the 3/8 hole is 2 11/16, vs the old one at 2 1/2. I don't know how important the length of that arm is - would the 3/16 excess length be an issue with these awning windows? In other words, is that better than the 39-378 witt the swing arm that is 1/16 shorter?