No, i think i have the reason why it doesnt work.
Your truck has ADD (not manual locking hubs)
when you turn your engine off, the vacuum is now gone and your 4wd will not be engaged (ADD runs on engine vaccum) therefore only 1 half of the differential will be connected to the t-case, allowing it to spin.

None of this hydraulic mumbo-jumbo, it's all in the pneumatics <img src="/forums/images/graemlins/smile.gif" alt="" />

89 4Runner
3" BL, M/T locks, 33"bfg mt, bilstein, Kayline, tubebumper, toyotafiberglass panels
TBI: Elocker,3.4 w/ORS,b+b,S2Sstg2cams,arias pistons,P+P intake,TRDs/c,URDpullies+7th,downey headers,MAPECU2,WEGO WB, SupraMAF,walboro255,stg4clutch, EPaOo2 sim