Hello Roger, The specifications are different between RS55190 and RS55123 such as the compressed length, extended length, travel length and the mounting codes. Should you need further assistance , feel free to call us at 1-866-529-0412.

I am going to put a six inch lift kit on my truck what would you recommend for my truck

Hi Jaime, The is used for stock replacement, upgrade performance shock absorber with up to 4 inches lift. Since you have not provided your exact vehicle application (year, make, model, submodel & engine size, RWD or 4WD), it is hard to pinpoint the shock absorber replacement you need. You actually can look it up by following the steps below. On the homepage, please enter your application, simply select your vehicle’s year, make, model, sub-model, and engine size and click “Go.” Once your application is selected, type the name of the part you need on the top search box and press enter. Once the part shows up on your screen, you’ll see a “Guaranteed to Fit, Direct fit” note/badge if the part will fit, and we recommend that you also double-check your vehicle fit details as well as the vehicle fitment information table on the product page.