I am looking to do my swap real soon but I want to find a economical way to find a new tranny. My stock tranny has over 300k miles on it and doenst shift very smoothly anymore. Would it be reasonable to find a low KM tranny at the local junkyard from a 5GC (6GCs are RARE in my city) and mate it with a 3SGTE? They are both S54 trannys right?
Using 5GC 5speed GT tranny in a 3SGTE swap? - 6G Celicas Forums
No they are not the same transmission. The 5th gen GT or GT-S has the s53 trans while the 6th gen GT has the s54. Yes you can use it for the swap, but its weaker then the s54 transmission.
98 Celica gt red- totaled deer94 Celica st black DD (bad weather beater)- totaled deer95 Celica gt silver- chassis sold88 Celica All-Trac (Burned to a crisp)94 Celica gt white (sold)In need of a rust free chassis!!!!
300k!? 
automatic or manual?
automatic or manual?
You can also rebuild your s54 too thats another option and maybe put in a LSD while your at it. 
"To Protect And To Serve The Wealthy" -POLICE
what about 94+ 2.2L 4Cyl Camrys? I would imagine Toyota would use S54 on both cars to save production costs?
Well if it infact is the s54 manual trans then yes.
98 Celica gt red- totaled deer94 Celica st black DD (bad weather beater)- totaled deer95 Celica gt silver- chassis sold88 Celica All-Trac (Burned to a crisp)94 Celica gt white (sold)In need of a rust free chassis!!!!
haha thanks guys! i pulled some service manuals (why did i do that in the first place? sorry guys) and found out that the only cars with a S54 is a 94+ celica or a NA MR2. The gearing with a S53 is the same but the input and output shaft part numbers are different. I wonder how much of a difference they made with the S53 VS 54.