I just danced this jig on a modified 49 Jimmy recently. If you haven't already, go to rockauto.com and start matching pics & specs. But thats no guarranty as there could be internal differences like required rod length etc.
You might try calling a booster & M/S rebuilder to see if they can help you. Many on a google search will want pics and will give you a rebuild or replace price.
Good luck
Dave