I replaced mine today, it was popping out of 5th gear. I've speed shifted too many times (that Saturn didn't have a chance) even chirped the tires going into 3rd a couple times. I have a tip if you can't get the shifter retainer to turn. Get some Horseshoe Washer Pliers, like these...

They grab and turn the retainer easily. They also come in handy for brake horseshoe clips, which is what they're made for. No more popping out of 5th, the old one was mush. Parts cost $20, shipping $12.60 takes about 20 minutes.

 

I have to admit I struggled with mine.
While bare handed turning the retainer to get it out was easy. However reinstalling it proved to be a bit difficult. I washed my hands before attempting to reinstall it. Pushing it down and turning it just made my clean fingers slip.

The only way I could get the ring to go back on correctly without tools was to clean the retainer and stuff my hands inside of some very clean rubber dish washing gloves.
I got one heck of a lot of grip that way and it went back in pretty easy.

 

I've had a hell of a time myself. Rubber gloves definitely give better grip.

 

These pliers made it a 2 second removal and install of the retainer. I was getting ready to modify a tool to do it but gave these a try first. You just grab the retainer at the flat spots, push down and turn. Surprised the FSM doesn't say to use them. The only thing that made me mad about this job was the high shipping charge from Marlin, didn't even get a decal with it.

 

I know what ya mean with the shipping. Seems like they all want right around $10 to ship a tiny part. I tried to get mine from MarlinCrawler but the lack of them answering the phone put me and a few others off. I ended up ordering the same parts from Yotamasters for very close to the same price. They answered the phone, answered my questions and three days later I had my parts. With two stickers I might add, but I'm not a sticker guy.

 

Got mine for my 1997 with two stickers....bought them from an Ebay reseller I believe.