Any tips on fitting the US Car Tool Sub Frame connectors?

Hey guys,

I just received the duster/dart sport sub frame connectors from US Car Tool. They look to be very well made. Right now I have the car on a rotisserie, so I will not be doing any welding yet. I will wait until the car has the suspension all installed. My question is in regards to fitting. How much did you guys have to grind off to get them to fit? The rear drivers side doesn't seem to want to line up....the front seems much better....any tips would be great...thanks.

Graeme