8.25 w/ 2/45:1 Woes and Confusion

I read somewhere that only 2.73:1 and up could be upgraded. It had something to do with the differential cases being different from the 2.56, 2.45, 2.21 cases.

Someone else asked the same question last year. http://www.forabodiesonly.com/mopar/showthread.php?t=281216