Context is key.
Has it been down for 30 days waiting on parts, or down for 30 days because they aren’t confident in the fix proposed?
Have there been other powertrain issues with the truck?
Have there been several other issues with the truck and/or any serious safety issue repairs?
If this is the only time it’s been serviced for something major, I’d say you’re jumping the gun on the buyback idea if they are just waiting on parts.
Tell the service manager to search for the parts at other local and not so local dealers, not just their supplier and report back to you with results. This inventory system Ford uses seems to have a default value of ‘national backorder’ if it’s not in stock. I don’t know how true that ‘national backorder’ really is, but several other users here have been successful at getting faster repairs by instructing the service manager to check with other dealers for available parts.
Now, if your truck has been in for repairs several times, and the repairs have not been nitpick items, meaning major stuff - drivability compromised, safety at risk, leaving you stranded, this would ‘significantly impair the use and fair market value’ of the truck and possibly be a candidate for a lemon lawsuit, but, this should be a last resort. They’re never quick to resolve and it’s an overall PITA. They take anywhere from 2-18 months to resolve and if you’ve got a lot of depreciation going on, then that’s eating away at your potential for recovery in the suit. I’m not saying don’t pursue this, just be aware it’s not a quick fix.
I’d suggest you impart upon the dealer the impact this is having on you. Open up a Ford C/S issue and request assistance. Plead your case well to both your service advisor and the service manager.