[SoTxButler]

The Fast Cars suspension is a bolt-on. There are four (4) bolts securing the K-member to the frame. Those four come out and the new suspension bolts in.

Now, this is true for a Butler and I feel certain it is the same for an Arntz. Check with Arthur, he fitted his Fast Cars himself and can guide you through the process.

Can't help on the bolt pattern.

Good Luck