G'day Jye
The S2A wreckers had an oil reservoir tank up against the tub bulkhead. The winch was then bolted to the floor immediately to the rear of the tank. Your tub floor holes do not match up with the tank and winch setup. Not only that, the holes appear to be too small to support a winch of this size.
Have a look underneath the tub and see if the holes are drilled through the underfloor cross-member. If so, this would be to give the bolt/nut more strength and would suggest that they were positioned for strength rather than at random. If they are not drilled through the cross-member then this would suggest that the object bolted to the floor was not of significant size or weight.
The first photo shows the wrecker winch and the second shows a wrecker tub that has had the winch holes patched over. The LHS middle patch probably has something to do with the oil tank pipework.