8.75 to 8.25 Swap Questions

As the title states, I am taking the 8.75 out of my swinger so I can have it narrowed down. I need the car to be driveable while the axle work is going on. I have an 8.25 out of an A body that I want to pit in it. Question is what is the difference in the length of the drive shaft between these two axles? I obviously don't want to modify it because it will be used again when the axle is done so do you think the same shaft will work with both axles? I am sure I will atleast have to change the rear u joint. Any help would be muchly appreciated!!