481 in 1981, difficulty of rebuild

In 1981 the D&S returned 481 to service after not running in 15+ years. I know the engine was rebuilt in the mid '60s, never operated, then hauled dead to Durango in Dec. 1968 by 473 on the last D&RGW movement between Alamosa and Durango.
Now to my questions.
The 481 sat in the Durango yards from '68 to '81 under no cover from the weather, and no security to protect it from treasure hunters.
1.How much work was necessary to restore this engine versus any of the rust buckets like the 480 and 482?
2.Did the rebuild help in the restoration, or had time and the elements negated the work done in the overhaul?
3.Of the Engines that have been restored on both railroads, which engine was likely the easiest, and the hardest to bring back into service?
4. What has been running in Durango this summer?
Thanks