The axle is located by spring bolts, the head of which is round to fit in the centering hole in the perch, the bolt goes through all the springs, holding them together when the 'U' bolts are loose. Loosen the 'U' bolts a little to inspect whether the bolt heads are both in the perch.

Ed

'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires.
'47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle.
'54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed.
'55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.