If you collect or read info on the Aussie M113 fleet here is some info seen during ARN research on the AWM document archives:
102 Field Workshop Commander Diary 21 August 68
"Great excitement. 19 APCs arrive, "all brand new, I hope. This will take some of the pressure off 102 for a while..."
Road testing tasks to get a road speed requirement, agreed to adjust down from max of 37mph to 32mph.
https://www.awm.gov.au/collection/records/awm95/14/2/awm95-14-2-16.pdf106 Field Workshop Commander Diary July 71
"In accordance with the HQ AFV request we have carried out a study of the failure pattern of M113A1 engines in this theatre since April 1969. The findings of that study are contained in this Annex."
"... the average engine mileage has remained fairly constant overall (Appendix 2 Table 7) at about 4300 miles..."
Features a very detailed annex re cylinder liner failures etc.
https://www.awm.gov.au/collection/records/awm95/14/3/awm95-14-3-21.pdf