Re: NG to SG

In the case of the 70 Class (C-19's) they needed switchers in their expanding standard gauge empire and they needed them faster than the builders could provide or they could afford, so they widened out some frames and made 'em 0-8-0s at Burnham. It was back in the 1890's. Once they had enough standard gauge power they rebuilt them to narrow gauge, 'cause they were the biggest thing the 3' lines had at the time and they needed them big time on Marshall and Cumbres. 401, 402, 405, 410 and 411 were all thusly converted to 800 class standard gaugers. When they came back they were rebuilt back into the 400 class, swapping numbers around so that none had their original.
K-27's 458 and 459 were sold to Mexico in 1939 for their narrow gauge lines and when the road was converted to standard so were the engines, into very small 2-8-2's!
So it has happened but why would anyone want to today?