02/28/2011. Remarks by Johan Visschedijk: "Japan received sixty Grumman Model 89 S2F-1 Trackers for the JMSDF, these were serialed 4101 to 4160. In 1970/1971 four were converted to target tugs, these were redesignated S2F-U, received new serials, 9151 (c/n 681, ex 4160), 9152 (c/n 680, ex 4159), 9153 (c/n 640, ex 4137), and 9154 (ex 4158), and were assigned to No. 61 Squadron."