QCH 4D55 parts

[Maxedoubt]

Hi guys- For some time, I have seen 4D55 parts (up to complete short blocks) from Quantico Cylinder Heads (QCH). I have seen them on eBay and on their own website. They don't offer much info in the way of national origin,and when I've messaged them from eBay they tell me different things every time: Australia, Korea, "High-Quality Aftermarket" etc.
Has anyone purchased from them, or can you offer any definite origin info?
Thanx in advance

[geezer101]

They source their heads from a plant in China. Pretty much the same as any other aftermarket OEM style head - https://www.yongyu.com/quantico-cylinder-heads/ (they do have a separate supplier for marine/industrial heads and engine components)

The places that Quantico are mentioning are only their shipping destinations. Mixed reviews about their business/customer interactions. I did see they make 4G54/G54B heads with the big port M28 type casting. Their cylinder heads appear to be decent quality though - good castings and machining.