An easy way to do this is make the mounts, bolt/weld to the frame and have them hang out the side oversized... ie leave them long. Then take your slider tube and place it where it should go with a floor jack to mark where to cut your frame mounts. From there it is a cut, chop weld and you're in business. One newbie slider mistake is a lot of folks don't leave enough clearance between the body and the top of the main slider tube. I wouldn't go less than a 1/2" gap. No gap sure does look nice but no matter how beefy you make the sliders they WILL flex and get into the body (the very thing you're trying to avoid) without that gap. Even my Slee step slider that are VERY well made flex under the weight of the cruiser... but they work as intended and have the 1/2" gap I am talking about. You probably knew this I just hate to see guys go through the fun (trouble) of making a set of sliders only to still bang into the body with them.