Would a 3gste trans swap easily into this? There’s a junkyard 93 Celica in my area and it seems to be in a decent shape.
You have a salvage yard with a 1993 Celica All-Trac in it (with 3S-GTE engine)? Where is that salvage yard?
No, you have a 6th Gen Celica (1994) and a 1993 Celica is a 5th Gen. The All-Trac has all wheel drive (AWD), so the transmission has an added transfer case and a drive shaft heading towards a rear differential. That transmission is not compatible in any way to your drive-train or the body of your Celica.
Go to www.car-part.com
and look for a manual transmission for your 1994 Celica from area salvage yards. I'm sure you will find something. When you find a suitable replacement, you'll have to determine if it is best to use the entire salvage transmission, or if it is best to disassemble both and just use the intact housing from the salvage transmission on yours. You might have to take everything to a good, respected transmission shop in your area to do all this. Others are suggesting welding your current setup. That's another option - just be aware welding on a transmission case tends to make the area more brittle, and it also greatly heats up the insides of the case and could damage components within the transmission. If you take the transmission out, then take it apart so you just have the transmission housing left, welding is best done that way.