There are a number of issues you should consider before embarking on this project.
1. If you have a late-2008 unibody MBP, you are undoubtedly aware that there was never any anti-glare option offered for that machine. So there is no anti-glare display that was made to work with it.
2. If you choose to replace only the LCD panel and not the entire display assembly — which is probably feasible but involves a great deal of painstaking work — you will also need to buy (separately) the aluminum bezel that takes the place of the glossy cover glass panel in models that came equipped with the nonglare screen. The bezel covers and protects the edges of the LCD and the delicate electronic connections there, and hides all that from view.
3. If you go that route, you will have to make sure that the cabling related to the display you are installing is identical to the cabling related to your original display. This means checking to make sure the cable lengths, connectors and routing both within the display assembly and hinge cover and within the lower case of the computer are all the same.
4. If you choose to replace the entire display assembly with one that contains a nonglare LCD, you will have the entire, intact glossy display assembly available to sell afterward. If you replace only the LCD panel, the LCD and glass cover panel that you remove will have much less resale value and are likely to be much harder to sell at all, because you won't practically be able to offer any warranty with them and because there are probably far fewer people willing to tackle the fussy, risky display disassembly process than are willing to replace the whole assembly as a unit.
5. Even if you choose to replace the entire assembly, you will need to verify that the cables dangling from the replacement display assembly are the right lengths and have the right connectors to tie into your lower case properly. Because the assembly will have come from a later MBP model than yours, cable routing and connectors may have changed from one to the other.
If this all sounds more daunting than you were expecting, you may want to consider just applying a nonglare film to the glass covering your present screen. If you aren't happy with the results, you can fall back on the replacement option.
