So E is just a regular sized nema17 stepper motor. I still think you should buy the 0.9 degree stepper motor. You will have to double the step count in marlin under the configuration.h tab but it will increase the quality of your prints to bring greater resolution to your extruder's feedrates. One like this one right here: https://www.ebay.com/itm/JKM-NEMA17-...979db3164b7662