The '49's are beautiful cars and extremely well-engineered. I can't think of anything specific to the '49's to be aware of beyond the usual mechanical and structural (particularly frame rust) and cosmetic things that a prudent buyer would want to verify on any car purchase. The pre-1956 Hydra-Matic transmission (which was used by Cadillacs and other GM and non-GM cars for years) is very sensitive to adjustment to make its characteristically somewhat abrupt shifts bearable and those who know those units well are getting fewer by the day. The pre-'51 units cannot be shifted directly from neutral (there is no Park) to reverse without gear clashing; you must pause in Dr or Lo and let the transmission engage before going on to reverse. The valve body of the post-war units was designed to force the driver to do this, but he should keep the necessity to pause in mind in case age and wear has eliminated the safety mechanism. There is a very small possibility that the car he is looking at is synchro-mesh instead of Hydra-Matic and it's a rugged unit.