The bulkheads, motor mount, diff pullies, steering post and spur gear are different, but besides that i think you could convert it over.
The 04 as great as it is on carpet (i feel its better than the 05, espically in stock) was never an amazing asphalt car though. Although for asphalt you defenantly want to run the stock chassis and maybe move the batteries up like the 3.5 xray chassis or the bmi 350.
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