You're better off contacting the belt manufacturer, but they usually have
requirements concerning angle etc. If you remember when Earnhardt died,
NASCAR tried to put the blame on Simpson, but Simpson stated that E didn't
anchor the belts according to their specs, even after Simpson told E
face-to-face the mounting wasn't safe. Make sure you anchor the shoulder
belts correctly too.

It depends where the factory seat belt spots are located. I've used the rear
shelf points linked together with a piece of 1/4 plate, then relocated holes
as needed in the plate, but in most cases I've attatched them to a roll
cage. Fortunately, I've never needed to test the attatchment in a collision.

So, yes, you will likely have to fabricate some addition parts or plate in
some new mounting points to fulfil the manufacturer's requirements.

Stewart DIBBS