Updating an Abrams you say? There are lots of goodies out there. The Eduard Big Ed set is pretty good as a start. AFV Club makes T-158 tracks, Echelon makes very good decals for it. Both Real Model and Legend make some very good stowage sets with lots of extra goodies like corrected drive sprocketts, tow bars etc. Several companies make metal barrels. I used one from Modelpoint for mine. Futher on you could have a look at MR Models stuff. There you can get tow wires, antenna bases etc.
Erik