Does your existing box go through the left frame rail to the pitman arm, then forward to a J shaped steering arm attached to the left front wheel with the tie rod behind the axle?
If so, there is a 400 series box recently available that is made to fit that application using everything from drag link forward. Box has a gold irridate plate with many flathead bolts for attaching to truck frame. Look on E-bay.
Other options include moving the box in front of the axle, using the same drag link, might need to adjust length, if the tie rod is in front of the axle with crosswise drag link, get a GM Saginaw box and move the pitman arm to the crosswise position. This last paragraph applies to all trucks, not just GM
This is the CPP unit mentioned below.
Last edited by EdPruss; Mon Jan 04 2021 01:58 PM.
'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.