Originally Posted by Gerle
The second generation Altima, 1998-2001, only came with the KA24DE......
Yes, the 01 was the last year before Nissan/(Renault) introduced the 2.5L QR25DE with pre catalytic converters, commonly known as "pre-cats" which failed and relatively quickly rendered the 2.5L engines terminal. 2002-2003 Altima and Sentra models and thier owners were the primary victims of the terminal defect. Knowing that, not surprised the OP found the 01 Altima rather impressive, as opposed to the later two years which would be unlikely to make it to his shop in the same condition to be impressed. Likely most of them in bone yards long ago.