Has anyone put late model road king shocks on there 2010 street glide to get a better ride and did it work?
Or should I just go for the progressive shocks?

 

I did. Traded with my buddy as soon as I got the bike.

Ride quality? Solo, the SG shocks ride better. Two-up, the RK shocks ride better. I've tested from 0-50psi on both.

Seriously, I think Progressives will be better, but I'm not into spending the $500+ without riding a bike that has them first.

For now, I'm content switching out shocks depending on what I'm doing.

 

i got some full length 09 roadglide shocks and put them on my 08 streetglide and that extra inch of rear suspension makes for a big improvement in the ride. i'm tall so raising the rear of the bike a bit didn't cause any issues for me. stay away from the 2011 roadglide shocks or road glide custom shocks, as they're the same length as your streetglide. you could likely trade your short shocks for full length harley touring shocks from an ultra classic, classic, or standard electraglide, or like you mentioned, the road king, but remember like i mentioned, the rk custom has the short shocks like the streetglide and new roadglides have if i'm not mistaken.

 

Also be aware that the '08-previous shocks have softer compression/dampening settings than do the '09-up shocks. The earlier shocks ride way smoother.