The chain drive cases came only on auto trans in 87. What you will nee to find is any gear driven case after 81. the best to get would be a top shifting case that came from an EFI truck. Your truck may have a forward shift case in it now, or a top shifter like in the top pic on Cruzilla's post.
If you can only find a forward shifting case Marlin does sell the conversion kit. It could also be a good time to put in a short throw shifter.
If your stock case is forward shift you can leave it in as the crawl box and put the top shift in the rear. If you have a top shift case, then you can build the new case as the crawl box and put it between.
Or I could be wrong and the mediction is talking.
