UT99.org | Unreal Tournament Community

If Unreal Tournament and Unreal have the same engine and parts of the code, would it be possible for someone adept at Unreal Tournament modding to do a mod for Unreal? Just wondering, because I need an Unreal mod done, and I can`t find any forums for the original Unreal.

http://www.oldunreal.com
http://www.unrealsp.org mostly a single player campaign making community for both games.

A mod made in UT doesn't necessarily work in Unreal, and the other way around is also true. Thus it may or not work, it depends on the features and dependencies you use for your mod. If you use features which are in the UT engine but not in the Unreal one, you cannot use it in Unreal. If you use certain dependencies in your UT mod (like the Botpack), since Unreal doesn't have it it's also unplayable in Unreal.

Furthermore, the engine used in Unreal is right now very different from the UT one, given that Smirftsh is working in the Unreal one and releasing patches, not only to fix stuff, but to actually modify certain things and adding features which do not exist in the UT one.
Generally whenever you want to make a mod both for UT and Unreal, you should make it for UT first (given that it has less features than Unreal, but those features are still generally common to an extent), then try to port it to Unreal (by adapting some of the stuff there or even remake parts of it to work in Unreal).