Hi, I’m also a young builder and know how frustrating it can be to design your first trial truck. About your question... you can use 3L universal joints because they are more compatible with Lego technic pieces. Other options include the piece found in this trial truck http://www.nico71.fr/wp-content/gallery/ladaniva/frontaxlepend1.jpg. And no i dont know exactly where to buy power puller wheels. Maybe you should try bricklink. Try your luck
Hi, I’m also a young builder and know how frustrating it can be to design your first trial truck. About your question... you can use 3L universal joints because they are more compatible with Lego technic pieces. Other options include the piece found in this trial truck http://www.nico71.fr/wp-content/gallery/ladaniva/frontaxlepend1.jpg. And no i dont know exactly where to buy power puller wheels. Maybe you should try bricklink. Try your luck