Yep, I passed on the 2500 rearend. The search continues. I didn't realize how narrow the rearend on the AD was.
I Spent the day at an old salvage yard crawling all over a dozen late 60's early 70's chevys looking for a HO52 third member but they had already been scavenged. On the bright side I did find about 10 1948-54 trucks and scored a nice Harris Heater and some chrome trim parts I was needing.