Infantryman again, traditionally.
But, with their only relevant experience being during SISPEC BSLC
days, they tend to be completely out of their depth if posted to
reservist SIR or SAR units. Hence, from what I know, it's usually
those doing defense ops (PDF, SADA, FDS, etc.) who pick them up.
Too bad, cuz IMO the ex-PTIs usually have the fitness for even
recce trooper, just not the expertise. No, the SAF seldom re-course
non-regulars.
A lot just stay on the holding list too, but can be posted all over
the place. My Arty unit nabbed one during mid-cycle to join our RSM
group. The new job entails mostly "traffic cop/signal" stuff
(without revealing too much), so the learning curve wasn't too
difficult.