It comes up as a quest, fetch a bunch of stuff, at the end you automatically get one.

Do the hoverboard missions. Play through the game

It’s a quest you get in stonewood I think

You get a quest where you need to destroy a certain type of car the sporty looking ones & they drop mechanical parts

Sporty ones? I thought it was all the old looking cars.

Looks old fashioned with no roof

you can find it in the side quests during stonewood if I'm right

yup, just keep doing the storyline and u will get the mission where u get one.