What size hex bolt on 6.0 L block?

[raidermark]

Does anyone know what size the engine block hex drain bolt for the anti-freeze is on a 2007 6.0L GMC Yukon engine. I want to flush the cooling system. It looks like it may be a 3/4" inverted hex bolt but I'm concerned it may be metric. I'll have to buy an oversized hex wrench set so I want to get the right one.

 

[yonyon]

Considering that 3/4" is about 19.05mm or 19mm is about 0.748 in. it shouldn't be that big of an issue. Fudge it a little.

 

[ls1mike]

It is probablly Metric. I don't think any fastener/plug on an LSX is standard. 3/4 will work.