Not a tomb, same place as the ofrenda for Jackie. El Coyote Cojo bar in Heywood. Since CDPR mysteriously chose to mark/hide all locations on the map behind generic functionality instead of actual place names, you might have to hit a few bars depending on how many there are in the area.
sorry a little offtopic but i cant yet create threads cuz im new. i have long completed the heroes quest and gotten his tuned arch bike and his two guns and suddently i got a 3rd key in my backpack and it was marked as "new". the key is called "key to jackie's stash", its legendary and the description says "opens the storage container where jackie keeps some odds and ends". i dont think it is related to the heroes questline since there you only get two keys (key to jackies bike and key to jackies room). or am i wrong? is this the garage key or is there somewhere a container that i have not found yet?