yes, Canadian Desoto's had 265 in them, when I bought the car I did expect it to be a 251, but as I did some research I found that the all 53 and 54 Desoto's had 265 in them, Mine has the origanol motor as well, I had bought the car from same family that had bought it new, they indicated the motor has not been changed, the stamping on the block is S-20 the same model as the car. I have also just recently purchased a 53 Desoto (parts Car) it also still has the 265 full flow oil system block as well