They want an NDA (non-disclosure) for accepting the compensation? This is standard verbiage on most releases, and more to keep the company from having others PILE ON with their hands out, looking for compensation too. Without any accompanying enforcement verbiage (penalties) for violating and disclosing, there's no actual enforcement they could take against you FOR DISCLOSING. Though they likely wouldn't be happy if you posted it to FB groups and urged others to get $$ from them based on your good fortune.
The part that says "though and including the date of execution" - which means ALL ISSUES PRIOR TO AND INCLUDING THE DATE OF EXECUTION. It doesn't preclude any claims for OCCURRENCES AFTER you execute the agreement.
Now - if you want to hold out and try and get some "lifetime maxcare" extended service plan, in lieu of the $1,800 check - you can TRY. The settlement if for the "loss of use and inconvenience" of the truck being in and out of the shop for so long. And to try and head off a lemon law claim and them potentially having to take the truck back (the terms of which vary from state to state).
Personally - I'd take the check and buy some accessories. It's pretty much "found money". If the same issue occurs again - despite cashing the check, you would likely STILL HAVE ADDITIONAL RECOURSE - via your particular states Lemon Law.
I'm not a lawyer - but I WORK FOR LAWYERS for 40 years - so I'm pretty up on how this stuff works. Many of my clients call me for advice on stuff like Florida Gun Law (which I am VERY UP ON), and most think my talents are wasted as an IT guy, and I would make a GREAT LAWYER (but I'm already going to hell, why make my spot even HOTTER - LOL)...
Rick