483 was worn out after 1977. The repairs needed were heavier than the shop could do at the time. The biggest thing, as I remember, was the rear tube sheet needed to be replaced, among other heavier repairs.
Well today's C&TS can do all the repairs on 483, but since then poor ol' 483 has lost a bunch of parts to keep the other K-Series running and a bunch of parts went with 482 to Durango as part of the trade.
I guess it seems that even though they can do all the repairs needed on 483, there are just less repairs needed to revive 489.
Also the Tender on 483 would need to be completely rebuilt. Earl Knoob noted on this board a while back that 483's Tender still has the twist in the frame from the 1958 roll over just out of Durango. So I guess if you are going to replace the Cistern, then take the twist out of the frame. I would think Tender Trucks parts are also missing.
Kevin Cook