BILL J - I've never had a problem with the spring-loaded rear attaching pins coming out once they snapped in. I do have some clearance between the brackets that hold the pins and the back bars on the mule drive, but not enough for the pins to come out.
There was a discussion on another forum about "stripping kits" last spring. Guy wanted to make something quick & "Inexpensive" to try. EVERYBODY had their own idea of what Other brand of parts to buy, steel, stainless steel, some suggested sealed greaseless bearings, some thought Oilite bronze bushings would work. I suggested using hardwood, preferably Oak. Cut the roller segments out with a 2-1/2 to 3" hole saw, then bore the center hole out to 1/2" dia, sand the rough spots off and slide them over a length of 1/2" rod to suit the width of the mower. Well, everybody said that the wood wouldn't hold up but the guy eventually made the rollers from wood. They must have worked O-K because that was in April or May, and he hasn't posted about having a problem with them.
I replaced the worn-out plastic roller, (maybe it was wood, can't remember for sure, but it was one-piece) on the frt of my 38" deck about 25 yrs ago with four roller segments made from pine 2X4's. They still haven't worn as much as the plastic/wood? roller was. I made an internal anti-scalp roller for my 50C deck about 14-15 inches wide, mounts behind the center blade inside the mower deck 2-1/2 yrs ago. Those segments were made from Oak 2X4's, and granted we haven't used the mowers much this summer in the midwest, but they have taken a LOT of abuse and have held up really well. They make the space between the tire tracks appear "striped", which with the 12" wide rear tires covers almost all of the 50 inch width of the deck.
Some people have just attached a piece of heavy chain behind their mower decks to stripe the grass, but be careful when mowing when backing up. Steel chain & running mower decks don't mix well.