Drop Shocks Too Short?

[Turbo85GMC]

I had the rear of the truck up in the air supported by the frame rails, so the rear axle was hanging on the springs. I bolted up the top of the shocks, but I wasn't supprised that they didn't reach the brackets on the axle since it was hanging. I swapped the jack stands around to be under the axle, so the suspension would compress to normal ride height. The driver's side shock slipped in perfectly, but the passenger's side was still a good 1.5" from bolting up! What's up with that?!?

I ordered the shocks way back from Sport Truck Direct along with most of the other lowering gear. I've got a flip kit and drop shackle for a 7" drop (which I told the guy) The shocks they sent are Doetsch #4809G. Coincidentally, they were the same front (2.5" spindle + 2" spring) and rear.

What I really don't understand is why one of the rear shocks fit fine, and the other one didn't? Am I supposed to have two different length shocks in the rear when using a flip kit? I know that a flip kit relocates the axle rearward slightly because of the driveshaft, and that the Passenger's side shock mounts towards the front.

What rear shocks did anyone else use with a 7" drop out back?