right the tank on my xr3i has split ans started to leak

what are the differences between

non injection
mfi
efi

tanks, i no my fuel pump in on the inside of the tank, so maybe the RS one only fit

but surely all the tanks are the same shape size etc, im having trouble finding a direct replacement a tank

 

The injection tanks XR/RS have a swirl pot to collect/hold fuel going round corners, I dont think the carbs do

Ally