As far as I know the Donahoe Racing, (DRE or DRs), coilovers are only available in one size ... for stock Titans. They have a 2.5" body which means their internal reservoir holds more oil than if they were a 2" diameter body. They also have an internal bumpstop.

Just like OEM coilovers, they can be used on a bracket lifted Titan, such as a Procomp stage 1 kit.

For the PRG 4" Performance Package, PRG adds a spacer, an external bumpstop, and aftermarket A-arms to allow for greater lift and travel over their original design capabilities.

SAWs, (Sway A Way by Racerunner), coilovers are now available in three lengths: stock; the ones used in the 4" Performance Pkg. ... requires aftermarket upper A-arms; and for bracket lifted, like the Procomp. Since the stock ones and DRs can be used with the bracket lifts, I don't know why they, (or Greg), has the new dedicated size for bracket lifted Titans, unless it's for greater lift, or maybe for longer stiffer springs for more stability because of these trucks having a higher center of gravity. Just a guess though.

SAW rears. 2 1/2" probably would stay cooler longer because of more oil than the 2 1/4", but Greg said the new 2 1/4" ones will allow for more travel, and should mount easier. Details are not available yet, and he hasn't even valved them for a 4x4 yet. But soon.

Many of the products he sells are not one size fits all, so he wants to talk with people to find out their application before they purchase. An example of this is the aftermarket upper A-arms not being needed on the DRs or 2" Radflo coilovers ... for stock Titans. When I got my DRs, he told me there wasn't any reason whatsoever to get aftermarket uppers, with the DRs in the stock application.

Another example, someone wanting highest lift, might be advised to get a certain coilover along with a certain bracket lift kit, yet another bracket lifted Titan might want the best to try and act like a prerunner, yet another for slow rock crawling. Then 2WD vs. 4x4 differences complicates things too.