Thanks, it seemed to me they were the same just with the addition of the reservoir. One huge difference though, the 5160's are backordered from Bilstein for 16 weeks! I tried a lot of online merchants and they were all out of stock but I ended up going with AJ-USA since they had the best price. The 6112 are shipping immediately and I was wondering why "it is recommended that the driver side circlip is installed two positions higher than the passenger side circlip." Only the KDSS models are even on both sides