Cheapest way to lock up a non sure grip?

I caint believe we're actually advising somebody to do this. lol

Dont worry to much. This will not be used on the street at all. I have a perfectly set up 3.55 with a sure grip that I renovated and put together myself. However, that cost a lot of money because these things is not something you can go to your local store and pick up. Everything has to be ordered and shipped and pay customs etc. I just cant afford spending that money on this 4.86 unit. But at the same time Im super curios on how the Duster will perform with 4.86 out back!