I just did mine 2 months ago, but I forgot which size... However, it was either 8mm x 1.25 thread or 10mm x 1.50 thread... It can't hurt buying 2 of each and have it laying in a "bolt box"...
That's what I have; a bolt box... I just found what I was looking for when I needed it...
If you rent a steering wheel puller (free) at AutoZone, it will have the sizes you need... The harmonic balancer puller won't work for a lot of vehicles anymore... The spacing is very tight on a lot of vehicles; the harmonic puller is not usually designed for 2 bolts that are pretty close together...
Hope that helps...
Mike