So this past winter I purchased a double z frame from Riley Automotive. At the time I wasnt factoring in a quick change on the rear end. The frame comes standard to accept a '40 rear spring....which we all know doesnt work with a QC. So now, Im trying to figure out my options. Here is what I know about the frame.....113.5 inch frame, 106 inch wheelbase (center spring hole to center spring hole), center rear crossmember from centerline of axle is 7.5".......... To place a Model A rear crossmember in the rails....would I just have to locate it 7.5" in wards from the center hole of the '40 style rear CM to center hole of Model A rear CM? Plus change the rear end spring perches to model A on my '41 Ford rear...or the '39 which ever I use. Side note....this isnt a thread to complain about Riley Automotive or Eric, we all havent had bad experiences...so lets keep this on topic. Thanks!