What is the correct glow plug for the Tower Hobbies .46ABC engine?

[link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXJA86&P=0]TH Engine[/link]

Their link is to a OS#8 which I ordered but it is much shorter than the one installed in the engine originally.
[link=http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXCB27&P=V]their suggestion[/link]

I looked for some "long" OS ones but they were suggested for use in trucks...

Which is the right one? (with link)

Thanks.