When I went for the MoT last year the rubber boots on both ends of the track rod were perished and falling to bits. Rather than mess around I just got the complete Lemforder track rod kit so track rod with a ball joint on one end, track rod end and adjuster and fitted that. Took the car in for this years MoT yesterday expecting all to be fine and it failed on track rod ball joint boot split. Now my local factors stocks random sized boots for a quid each so I shot straight down there and picked one up. Split the taper and took the split boot off and found the ball joint itself was perfect and still had the original grease in it but the boot was falling to pieces. It doesn't look to be made of rubber either, more like a sort of rubbery plastic (vinyl?). Whatever it was made off, it doesn't last like old fashioned rubber does. It may not perish but it splits instead but I would have expected it to last longer than 12 months (admittedly that's 23,000 miles). So if you've fitted Lemforder expecting to fit and forget, think again.