I have a set of three extension tubes made by Spiratone for a Nikon F with photomic meter. The individual tubes are 13mm, 18mm, and 36mm. They can be used singly or stacked together. They will couple to the meter, but the short one is a little dicey; I'm not sure the design is great. You may have to hold it in place. But take a look. I used them many times before I "moved up" to my FM2.
$40 shipped.
$40 shipped.