Just wanted to pop back here to thank you for the reply - I picked one of these up yesterday from Sams. Fits just fine as a drop in but I think I will make a spacer so the hold down has more contact area. If it lasts, these are probably the best buy in AGM batteries right now from what I can tell.Drops right in using existing base and hold-down, there are guys from this forum where I got the idea who have fitted a board under the battery to raise it up a bit to secure it a little bit better and others who just drop in. I chose to drop in and it's held in place really tight by the existing hold-down just angled a bit instead of being level.