I have a 1984 E30+, and am not sure what you mean by "spreader lights" on your boat. On mine, I have a deck light which shines down on the foredeck--it is mounted on the mast at the lowest set of spreaders. I also have a steaming light that shines up/out for when motoring at night, it's a bit higher on the mast. None are on the actual spreaders on our 1984 E30+.
Neither is hard to replace, and bulbs are readily available. However, are you sure that it's the bulbs that need to be replaced, or could the connections be bad? On our boat, the connections for all the mast lights are inside the mast, about a foot above the mast step. It requires raising the mast a couple of feet in a sling, re-doing the connections and then lowering the mast.
Frank