the pullstart version is a threaded crank version.
you need a SG crank or a clutch adapter.
traxxas has a clutch adapter that works with the TZ in the revo.
one of the other versions of the TZ is the bump start version which has an
SG crank but it is a different length and has no ring cut on the end of it for a E clip.
for that version you need to cut the crank and install a clutch adapter.
very easy to do.
the TZ lays down some serious power
i have owned several of them