According to a source close to United, Ngubane has already agreed on a two-year contract with the Chilli Boys.
"Ngubane is signing with us," says the informant.
"He is expected to be in Port Elizabeth either tomorrow or Wednesday. We are expecting another defender from Congo."
The Port Elizabeth-based outfit have recruited the likes of Bongani Ndulula, Menzi Masuku, Thembinkosi Lorch and David Zulu in the off-season.