As per the top of this post, Brad Hanrahan has a Tuxedo black LH SLR5000 with 60Y trim. It has its original inserts afaik and they look like Chevron (see below).
You'll find Leroy has labelled it wrong, the photo could belong to a 60Y tagged car but it may be 60X too as you say.
60A/B/Z are HJ update Chamois/Black trims from around 4-5/76. 60V/X/Y are earlier HJ Chamois/Covert.
What is interesting although treat it with only 50% confidence as parts catalogues can be deceptive, the later HJ parts catalogue lists as the same seat covers for 60B and 60Z:
60B and 60Z - 9932415EY
60Y is 9934215ES, 60X is 9932415DV, 60V is 9932414DV and 60A is 9932414EY.
If this is true then 60B and 60Z should both be Chevron (but 60Z may not have been available so they made it the same part number as 60B).
So it is only 60X and 60Y that are confusing which you already know! What is interesting though in HJ Kingswood 60V and 60A share the same part number for the seat cover 9932938DV, and 60B & 60Y do the same 9942251EY, but 60X is different 9942251DV. So for Kingswood this would suggest that 60Y/B are both Chevron - but the fact that for GTS 60V and 60A use a different cover suggest something other than the insert differs between them so it makes sense then that 60B and 60Y in GTS are a different number. Which lends credence to your theory that 60Y (and 60B) are Chevron so 60X must be Raydo. 60Z must also be Raydo (if you believe the HJ parts catalogue) but with something else different?
Note that there is no 60Y trim listed in the HJ release parts catalogue, only 60V and 60X.= and the numbers are the same as listed in the late catalogue.
Herringbone is the black and white Ranier trim used in 18X in HX. Norm Darwin has this listed in Torana tough for 60X but I don't think it is right - however it could be as it is used on 18X trim in HX and LX and it is the only X trim that existed in HX and LX, so maybe HJ was the same?
Here is Brad's seats and body plate:
http://s70.photobucket.c...6.jpg.html?sort=3&o=103
http://s70.photobucket.c...5.jpg.html?sort=3&o=150
I assume Brad has done the car using black where it would normally be Covert.
EDIT - I just noticed Norm has 60X in earlier LH as Ranier (herringbone) and 60Y as B&W Raydo. SO if this is the case my bet is the insert changed in HJ with LX release. So the answer may be that 60Y is both Raydo and Chevron, just depends on when? I've asked Norm if he has the HJ colour/trim album.