Cummins12V98 wrote:
4600 and 5100 other than color are internally the EXACT same shock. 4600 for stock and 5100 for stock and up to 2" lift.
Having had both 4600s and 5100s on numerous trucks, I can tell you that even if they are the same, the 4600s ride better than the 5100s. I had 4600s on my 04 Duramax and it rode great, when I sold it I took them off and put them on my FIL's 05 Duramax. Still going strong with over 65,000 towing miles on them. My BIL has an 05 6.0L Chevy that we put the 5100s on, it rides a little softer than the 4600s. I put 5100s on my parents 09 Duramax, ride is softer than the 4600s. I have 5100s on my 13 Duramax, much better ride than the stock shocks but they do have more bounce seems like.
If I could do it all over again I would stick with the 4600s on all the rigs. I do agree the 5100s look better and stay looking better longer.