Don't get RS9000's, consider Gabriel VST's
I have RS9000's on my 97 Ranger, and they're perfect for a pickup. When I carry something heavy in back, I crank them up. Excellent stability and control.
HOWEVER - it rides like a truck. I have no idea what the ES9000's are, but for that price, they are not a "premium" shock. See the pricing on the Monroe's below.
My wife's 98 Explorer blew the factory (very crummy) shocks at 26K. I put on $38/ea Monroe SensaTracs. They lasted about 40K, probably should have replaced them at 35K.
They improved the right somewhat, and totally eliminated the side-to-side roll the factory shocks allowed. Big improvement. However, they are street shocks and were not up to the abuse of all the offroading we do.
I want to get either the new Explorer ProComp monotube adjustables ($90 each) or the new SwayAway large bore offroad shocks. Explorers seem to be low on the list for these new products, and I'm not inclined to settle for Bilstein's. Hurry up and wait.
SO - I went to Pep Boys and got 4 Gabriel VST's for $86 out the door. I won't feel bad throwing them away when the real shocks come in.
They, like the factory shocks and the Monroe's, are too short. The front shocks are about .5 - .67" too short, but that's life. I haven't seen the extensions you mentioned, but that's a good idea if you have any kind of lift.
The ride quality is very good, probably because the Monroe's were pretty shot by the time I swapped them.
You get what you pay for in shocks, as in tires. Figure montoubes or adjustable twin-tubes at $75 or so each (e.g. Bilstein or Rancho RS9000) and adjustable monotubes at >$90.
For $20 a piece, the Gabriels are a darn good step up from the factory $5 shocks.
Regards,
Brian in CA