67 Rear end 5 lug conversion problem

[HookEm67]

So I ordered a 5 lug disc brake conversion and 5 lug rear axle conversion kit from ECE. To my surprise I found out that my rear end has been replaced somewhere down the line as the 63-69 conversion axles I ordered were too short. ECE is awesome to work with as they will swap them out for the 70-72 axles as long as I ship the incorrect axles back. My question is should I send them back (shipping will be on my dime and run me about $70, each way I assume) or look for another rear end that will accept the 63-69 axles? Do I have any other options? I currently have a non posi with 3.08 gears that I would like to upgrade to a posi with 3.42-3.73 gear ratio.