Have a look at other models, you'll be surprised.
Some time ago, I was the EHCC of Victoria's car show at Albert Park and I noticed that there was an original EJ ute with a spare wheel clamp similar to the one in the picture, shown above.
I thought if this clamp was unique to EJ's and EH's or not, as I need it for EH van. I didnt think much of it until I took an original HR Special for a test drive one day and I noticed that the spare wheel clamp was identical to the one I saw at Albert Park. I then found quite a few on EJ's and EH's and HR's.
I think what happened is that Holden has made thousands of these clamps, and they carried them through their model ranges until they ran out of stock.
I might be wrong but worth a try.
Sean