The Gerat Nr would normally be preceded by a number 8 for an airframe component, or another number as applicable.
In this case, with the clear Dornier plate and the sub-contractors details, I suggest that it possibly is from a Do 217 airframe Gerat, particularly numbered 8-217.234-04 . The Werk Nr seems to be low (243 E 2), suggesting that it is a fairly individual part.
Further exploration really needs the correct Do 217 Ersatzteilliste, possibly for the E2 version?
Eng