Can't give you the bolt size, but I have never removed a harmonic balancer and/or pulley setup w/o removing the radiator. It's in the way, you can really carve up your hands, you stand a good chance of damaging it, and, if you need to use a puller, you gotta have some space to work. You may also need a seal extractor tool if you don't remove the front cover, (not usually necessary).

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Jeff Lawrence
1989 300e
2000 Dodge Grand Caravan SE
No matter what you fix, there will always be something else to fix..
"Warranty" is just another way of postponing the inevitable.