During the 1960s most of the narrowgauge railways wereconverted tostandard gauge, and SJ chose to rebuild the locomotives to this gauge, and also change the axle system to D, giving them the designationT23. Of the remaining ten Tps, six were scrapped in the 1970s while the last four remained in service until the 1980s. The latter have all been preserved.
Locomotive types initalics are in production. G-type locomotives have diesel-hydraulic transmissions, DE-type locomotives have diesel-electric transmissions.