Help finding make of knife from my grandad

So my granddad died a few months ago and I’ve Inherited his car, when searching in one of the back seats I find this knife which used to be his. It’s definitely been in much better condition and I’m aiming to restore it to a better condition (which may require a blade replacement)I’m mainly curious as to what brand it is as one of the blades has a branding but it’s been sharpened so much I can’t make out much of it, only the words stack knife. Any help with finding out about it and any advice on restoring a z maintain the knife would be useful 🙂

by FlyingHighOnRapture