IMHO If she starts...... no you don't need one. Even better than a decompression setup to keep it that way is good maintenance, keep it under a walled shelter in winter esp. and add an engine coolant heater to use in the winter.
Thanks for the response. She never stays out it weather. I use the glow plugs on the first start of the day,starts right up after 3 revolutions even when temp. is the upper 20's,5-6 in the teens to zero.