In case you still need the info, the brake hardline is 3/16", GM part # 88983905. The part is listed as "3/16" x 16ft, bulk tubing"
so I wouldn't bother ordering it from GM since it lists for $73.34 and you'd still have to bend it yourself. Amazon has it for $34.66 here
or you can always get one that's already pre-bent off a donor/parts car locally.
Here's the diagram I'm referencing: link
The diagram shows a coupler that'll join the two lines mid body, so it's not one continuous piece to the ABS module (which makes sense, because both lines have the same part number i mentioned above). The joint uses two part numbers:
#3 GM#11569751 (M10x1.0x16 hex nut, inverted flare fitting)
#18 GM#11518565 (union fitting).
Note that #3 is used on both ends of the hardline so keep that in mind in case the end that connects to the brake hose gets stripped when you're removing it.
Lastly, attaching a new fitting to the line will require renting a double flare tool in order to flare out the end of the line after slipping on the new fitting. So in other words, getting a replacement off a parts car would really limit the headache (Ask me how I know lol).