Excuse the stupid question, ('Search' has failed me on this one!) but...
Are the drive belts the same for all three models? afaik they're all 369mm but is there a difference in width / tooth profile ???
Or to look at it another way, can the re-inforced DB01 belt (Tamiya part 54140) be used on the 'normal' 501x? (i.e. not the WE car)
Also, any downside to using the re-inforced belts? only thing I could possibly think of is that the stronger belt might increase the chance of damage elsewhere in the gear train in the event of something getting stuck / breaking? (Whereas the standard belt would just snap?)