There are 5 structural isomers, 3 of which can exist as 1 of 2 enantiomers, resulting in a total of 8 isomers:
: 1-chloro-1-deuterio-propane (2 enantiomers)
: 2-chloro-1-deuterio-propane (2 enantiomers)
: 3-chloro-1-deuterio-propane
: 1-chloro-2-deuterio-propane (2 enantiomers)
: 2-chloro-2-deuterio-propane
Note: there is much disagreement regarding the naming conventions of molecules including non-standard isotopes, such as deuterium here. I would like to hope that the names given above would at least be widely understood, even if not considered to be ‘correct’.