Antoninianus - Probus Cuirassed, left; SALVS AVG; Salus

According to RIC, RIC 748 was minted by the first (XXIP) to the seventh (XXIVII) officina of the Siscia mint. The original RIC text mentions 6 different variations/different bust types (bust types according to Pierre Bastiens grouping of bust types; see illustrated: probvs.net), and there are also multiple variants known:

1. radiate, cuirassed, right (B bust, Alföldi (*) 065.016-031 (example: probuscoins.fr #425), Numista #296616);
2. helmeted, radiate, cuirassed, left, holding spear in right hand and shield in left hand (E1 bust, Alföldi 065.044-050 (example: probuscoins.fr #424), Numista #296617);
3. radiate, wearing imperial mantle, left, holding sceptre surmounted by eagle in right hand (H2 bust, Alföldi 065.004-012 (example: probuscoins.fr #4980), Numista #296619);
4. radiate, cuirassed, left (B1 bust, Alföldi 065.032-036 (example: probuscoins.fr #1934), Numista #293789);
5. radiate, cuirassed, left, holding spear in right hand and shield in left hand (F1 bust, Alföldi 065.040 (example: probuscoins.fr #1932), Numista #293787);
6. radiate, cuirassed, left, holding spear (F5, Alföldi 065.037-039 (example: probuscoins.fr #2557), Numista #293790);
7. [var] radiate, draped, right (A bust, Alföldi 065.015 (no example on probuscoins.fr), Numista #293104);
8. [var] radiate, wearing imperial mantle, right, holding sceptre surmounted by eagle in right hand (H4 bust, Alföldi 065.013-014 (example: probuscoins.fr #444), Numista #293788);
9. [var] radiate, cuirassed, left, holding spear in right hand and shield in left hand, from behind (F8 bust, Alföldi 065.041-042 (example: probuscoins.fr #3202), not in Numista);
10. [var] helmeted, radiate, cuirassed, left, holding spear in right hand and shield in left hand, from behind (E2 bust, Alföldi 065.043 (example: probuscoins.fr #2555), not in Numista);
11. [var] radiate, cuirassed, right, holding spear (F9, Alföldi - (example: probuscoins.fr #3998), not in Numista);
12. [var] radiate, wearing imperial mantle, left (H bust, Alföldi 065.003 (example: probuscoins.fr #1936), not in Numista).

(*) Andreas Alföldi, Vorarbeiten zu einem Corpus der in Siscia geprägten römischen Kaisermünzen. Heft V. Verzeichnis der Antoniniane des Kaisers Probus, Budapest, 1939.

According to Pink, RIC 748, with its obverse legend nr. 8 ('IMP PROBVS PF AVG'), reverse legend 'SALVS AVG', depicting 'Salus, draped, standing right, feeding serpent held in arms', is part of the 5th (exergue-/officina mark style: -/-//XXIS) and the 7th emission (-/S//XXI), which was respectively in the year 278 and 280 (Karl Pink, Der Aufbau der römischen Münzprägung in der Kaiserzeit VI/I, Wien, 1949, p. 52).