I had Timbrens on my previous 350s--worked well. On my 450, no give, too harsh.
RAS could not fit my 450, no matter how hard the installer tried.
With a 2500 Suburban, I would think it would fit and work--and I think they have some sort of 'satisfaction' warranty?
If you try it, please report back the results.
Also, might want to consider a visit to a professional spring/axle shop with your concerns, they would have some idea what to do.
'05 36TK3 Mobile Suites
'10 F450 new to me
'09 F450 Lariat 4x4--died