There was one six cylinder Toyota Tundra engine used between 2000 and 2004, while there were two last generation Toyota Celica engines used between 2000 and 2005. The Toyota Tundra engine in question is a 3.4L 5VZ-FE engine which had a previously solid record in the Tacoma and T-100. The Toyota Celica engines in question are the 1ZZ-FE and 2ZZ-GE, which go in the GT and GTS, respectively.
When Toyota began to plan for a full sized truck, they knew the last thing that it needed was any type of engine problem. So, the Toyota Tundra engine was reused. In fact, the eight cylinder engine had a previous run in the Land Cruiser and Lexus LX470. The 5VZ-FE came out in 2000 with a Federal and California emissions version. From 2000-2004, the 3.4L was able to meet 50 state emission standards, meaning all engines not only passed Federal emissions standards, but those of California and New York.
It is common when installing a 5VZ-FE to find a stuck valve. In every instance I have personally encountered this, running the engine has been sufficient to unstick the valve. Normally, carbon buildup is the culprit, but the level of buildup only causes a stick when the engine isn’t run every day. In other words, if a valve is stuck, it is just barely.
When installing one of these 3.4’s, it is critical to note a few common differences between two and four wheel drive versions of the vehicles. Depending on the year, the oil pans and water pumps can vary, but these parts are easily swappable. Use your oil pan, and purchase a new water pump if you notice a difference. It is a good idea to replace your water pump anyways, even if it is the same. This makes it less likely that you will overheat your engine.
The last generation Toyota Celica engines are radically different from each other. Both are 1.8L motors (that have 2 cc displacement difference), but are radically different from each other. While they have virtually the same displacement, they have entirely difference performance curves. The easiest way to view the engines is that the 1ZZ-FE has more low end performance. Low end speed is gained quicker. The 2ZZ-GE beats the 1ZZ-FE on the top end with its higher horsepower. This is why the GTS gets a six speed manual transmission as an option. With a sixth gear, the C60 simply allows the GTS to handle high speeds in ways that the GT can only dream of.
Many consumers report great difficulty in finding low mileage Toyota Celica engines. This is due to several factors. The main factor at play is that this is an incredibly popular vehicle to tune and chip. Since this involves pushing the engine to beyond its recommended performance envelopes, many people simply blow their engine up. You rarely run into this on family sedans.