[David_Hayward (RIP)]

Yes, it's SR prefixed...only used on the 1942 C15s; 1942 C8s and C15As used MR and WR prefixes. This is the complete list of Holden-assembled to my knowledge:


2842100041S [SYDNEY-ASSEMBLED]
2842100047S NOW FITTED WITH ENGINE # TR3,970,956 [SYDNEY-ASSEMBLED]
2842100074 ENGINE # SR3,836,145 [HOLDEN-ASSEMBLED]
2-8421-00077 SR3,835,415 [HOLDEN-ASSEMBLED]
2842100091M ENGINE # SR3,851,790 [MELBOURNE-ASSEMBLED]
2842100100 [HOLDEN-ASSEMBLED] PRESERVED
2842100111P ENGINE # SR3,835,344 W.O.73 [PERTH-ASSEMBLED] 10/4/43
28421M00116M ENGINE # SR3,781.572 [MELBOURNE-ASSEMBLED]
2842100128P ENGINE# SR3,857,769 28 APRIL 1943 [PERTH-ASSEMBLED]
2842100166 ENGINE # SR3,781,498 WO1
2842100230M ENGINE SR3,779,337 WO1 [MELBOURNE-ASSEMBLED]
2842100244M ENGINE # SR3,779,671 [MELBOURNE-ASSEMBLED]
2842100317M ENGINE # PR3,835,385 [MELBOURNE-ASSEMBLED]
2842100360S ENGINE # SR3,857,660 [SYDNEY-ASSEMBLED]
2842100373S ENGINE # SR3,857,763 [SYDNEY-ASSEMBLED]
2842100380S ENGINE # SR3,857,947 [SYDNEY-ASSEMBLED]
2842100412S ENGINE # SR3,857,834 [SYDNEY-ASSEMBLED]
2842100415S ENGINE # SR3,857,753 [SYDNEY-ASSEMBLED]
2842100437S ENGINE # SR3,857,545 [SYDNEY-ASSEMBLED]
2842100441S ENGINE # SR3,857,847 [SYDNEY-ASSEMBLED]
2842100479M ENGINE # SR3,857,960 [MELBOURNE-ASSEMBLED] 1 MARCH 1943
2842100481S ENGINE # SR3,857,646 W.O.73 [SYDNEY-ASSEMBLED] NO ASSEMBLY DATE!
2842100490M ENGINE # PR3,849,145 [MELBOURNE-ASSEMBLED] 20 APRIL 1943
2842100506S ENGINE # PR3,857,638 [SYDNEY-ASSEMBLED]
2842100508S ENGINE # WR3,815,503 [SYDNEY-ASSEMBLED]
2842100518S ENGINE # PR3,857,842 [SYDNEY-ASSEMBLED]
2842100519S ENGINE # PR3,857,844 [SYDNEY-ASSEMBLED]
2842100538M ENGINE # SR3,8587,018 [MELBOURNE-ASSEMBLED] 16 MARCH 1943
2842100591M ENGINE # SR3,858,033 W.O. 73 MARCH 19 1943 [MELBOURNE-ASSEMBLED]
2842100592M [MELBOURNE-ASSEMBLED]
2842100609M ENGINE # SR3,858,180 [MELBOURNE-ASSEMBLED] 24 MARCH 1943
2842100613M ENGINE # PR3,858,216 [MELBOURNE-ASSEMBLED] 24 MARCH 1943
2842100615M ENGINE # SR3,858,215 [MELBOURNE-ASSEMBLED] 24 MARCH 1943
2842100706S ENGINE # SR3,857,699 W.O.73 [SYDNEY-ASSEMBLED] NO ASSEMBLY DATE!
2842100711M ENGINE # PR3,874,368 [MELBOURNE-ASSEMBLED] 14 SEPTEMBER 1943
2842100712M ENGINE # SR3,857,885 [MELBOURNE-ASSEMBLED] 7 APRIL 1943
2842100730M ENGINE # PR3,874,378 [MELBOURNE-ASSEMBLED]
28421000919 ENGINE # SR3,851,790 WO12 (WIRELESS) HOLDEN-ASSEMBLED

You can see that each plant used their own sequential series, and they do not relate to any other plant's sequence. I think it was Brisbane plant that did not always use 'B' in the serial. The Perth 'P' vehicles were possibly the rarest.