Drivetrain Rearend Help.

Have an 04 mach with stock rearend except using 4.10's.

I have been trying to locate new spider and side gears and had no luck so went to local Ford and he told me that for him he cant order because that gear carrier is listed as non-serviceable.

I have googled and googled for what I need and find nothing.

So anyone here know if I can just buy the spider and side gears or am I gonna have to drop around $500 for the whole diff carrier?
Are those gears really not replaceable? Im finding that odd since I know they can be removed,already done it when replacing all the bearings back there.

Thanks for any info.

I think I got this figured out, I think the local ford parts guy told me the part for a v6 somehow. Not sure how since I gave him my VIN.
Number he gave me for the carrier...2LZ5-4026-AA

A ford parts dealer in another state shows my car to be this part number....5R3Z4205AA

If I enter the first number it says dosnt fit an 04 mach. I search for my car and I get the 2nd number. Hopefully thats correct.