[Hooper]

I did mine last year and went with a closed array Simrad system in my '86 3600 Open. The mast (or mount) was easily through bolted to the hard top. One thing to note with closed array radar - take the antenna down if you shrink-wrap in the winter. The weight of the wrap on the antenna squishes the gasket that seals the antenna. It's only 4 bolts and one connector to remove.

I would recommend forgetting the spotlight and install a Lightbar instead. They're only around $600 and are a complete game changer. You turn that thing on and EVERYTHING is lit up. You can almost use it to substitute radar at night. It's very helpful when coming into a harbor, going through jetties, finding buoys and so on. It's one of the best things I've installed so far, there's no moving parts and all you need is a wire and a switch.