The Stratosphere version of the quirk Easy to Maintain (p.193) says:
- Some units, such as the Thorn, are easier to maintain and repair. All repair or replacement rolls made for a unit with this quirk receive a –1 target number modifier.
With the Difficult to Maintain quirk on p. 198 mirroring the text.
The rules as written don't actually state they apply to maintenance...
Also, do these quirks apply to customization?